A New Nanoid Titanosaur (Dinosauria: Sauropoda) from the Upper Cretaceous of Brazil

Abstract

Titanosaurian sauropods are known to exhibit remarkable body size disparity, with some taxa famed for nearing the zenith of terrestrial vertebrate body size. Here, we describe a new titanosaurian – Ibirania parva gen. et sp. nov. – from the Upper Cretaceous (Santonian–
Campanian) São José do Rio Preto Formation of Bauru Basin, in which represents one of the smallest sauropods known to date. The new taxon is diagnosed by seven autapomorphies and had an estimated body length of 5.7 m. Histological and μCT scan analyses showed that this new taxon is represented by skeletally mature individuals, which had attained somatic maturity prior to death. Phylogenetic analyses recovered the new taxon deeply nested within Saltasaurinae, a clade previously known by small-sized forms. Ibirania parva gen. et sp. nov. brings new information indicating that the body size reduction in some titanosaurians could be driven by recurrent ecophysiographical settings, present in South America prior to the diversity peak attained by the group during the Campanian–Maastrichtian.

Full text

A NEW NANOID TITANOSAUR
(DINOSAURIA: SAUROPODA)
FROM THE UPPER CRETACEOUS
OF BRAZIL
1Programa d e Pós-Graduação em Zoologia, Departame nto de Zoologia, Instituto de Bioc iências, Univers idade de São Pau lo, Rua do Matão (T ravessa 14) 3 21,
05508-09 0 São Paulo, SP , Brazil.
2Laborató rio de Paleonto logia e Herpetologia, M useu de Zoologia, Universidade de São P aulo, Avenida Nazaré 48 1, 04263-000 Sã o Paulo, SP, Br azil.
3Laborató rio de Paleoecologia e Paleoicnologia, Dep artamento de Ecologi a e Biologi a Evolutiva, Univers idade Federal de São Carlos, Rodovi a Washington Luís (SP-
310) km 235, 13565-905 São Carlos, SP, Brazil.
4Departam ento de Geologi a, Universidade Federal do Rio Grande do Norte, Rua das Engenh arias s/n, Lagoa Nova, 59078-970 Natal , RN, Brazil.
5Institut e of Geoscience s, University of Campin as, Rua Carlos Gomes 25 0, 13083-855 Ca mpinas, SP, Brazil.
6Museum f ür Naturkunde, Leibniz-Institut für Evolutions -und Biodiversitätsforschung, Invaliden straße 43, 1011 5 Berlin, Germany.
7Institut für Biologie, Humboldt Universität, I nvalidenstraße 42, 1011 7 Berlin, Germany.
8Laborató rio de Sistemáti ca e Tafonomia de Répteis Fósseis, Depart amento de Geolog ia e Paleontolog ia, Museu Nacion al, Universidad e Federal do Rio de Janeir o
s/n, 209 40-040 Rio de J aneiro, RJ, Bra zil.
9Museu de Paleontologia “Prof. Antônio Celso de Arruda Campos”, Centro de Artes, Praça do Centenário, 15910-0 00 Monte Alto, SP, Braz il.
10Museu de Paleontologi a “Pedro Candolo”, Esta ção Cultura, Praça Farm acêutico Bruno Garisto, 15890-0 00 Uchoa, SP, B razil.
11Centro de Ciências Hu manas e da Educação, Un iversidade Estadual do Norte do Paraná, Rua Pa dre de Melo 1200, 86400 -000 Jacarezinh o, PR, Brazil.
12Depart amento de Geolo gia Sedimentar e Ambien tal, Instituto de Geociências, Universidade de São Paulo, Rua do Lago, 562, 05508-080 São Paulo, SP, Brazil.
BRUNO A. NAVARRO1,2,3
ALINE M. GHILARDI3,4
TITO AURELIANO3,4,5
VERÓNICA DÍEZ DÍAZ6,7
KAMILA L. N. BANDEIRA8
ANDRÉ G. S. CATTARUZZI2
FABIANO V. IORI9,10
ARIEL M. MARTINE11
ALBERTO B. CARVALHO2
LUIZ E. ANELLI12
MARCELO A. FERNANDES3
HUSSAM ZAHER2
Submitted: 27 October 2021 - Accepted: 25 August 2022 - Published: 15 September 2022
To cite this article: Bruno A. Navarro, Aline M. Ghilardi, Tito Aureliano, Verónica Díez Díaz, Kamila L. N. Bandeira,
André G. S. Cattaruzzi, Fabiano V. Iori, Ariel M. Martine, Alberto B. Carvalho, Luiz E. Anelli, Marcelo A. Fernandes,
and Hussam Zaher (2022). A new nanoid titanosaur (Dinosauria: Sauropoda) from the Upper Cretaceous of Brazil.
Ameghiniana 59(5), 317–354.
To link to this article: http://dx.doi.org/10.5710/AMGH.25.08.2022.3477
PLEASE SCROLL DOWN FOR ARTICLE
A geologically older, less ossified
species of Baurubatrachus reveals
new osteological information that
provides novel characters.
NEW NEOBATRACHIA FROM THE
LATE CRETACEOUS OF BRAZIL
NEW NANOID TITANOSAUR FROM
THE UPPER CRETACEOUS OF BRAZIL
NEW PHOCIDAE FROM THE LATE
MIOCENE–PLIOCENE OF CHILE
A new saltasaurine from the
Bauru Basin brings new clues in
the evolutionary history of the last
titanosaurians.
The southernmost occurrence of a
fossil seal is recorded from the South
Pacific Ocean from Guafo Island in
Chilean Patagonia.

317
AMGHB2-0002-7014/12$00.00+.50
A NEW NANOID TITANOSAUR (DINOSAURIA: SAUROPODA) FROM
THE UPPER CRETACEOUS OF BRAZIL
BRUNO A. NAVARRO1,2,3, ALINE M. GHILARDI3 ,4, TITO AURELIANO3,4,5, VERÓNICA DÍEZ DÍAZ6,7, KAMILA L. N. BANDEIRA8, ANDRÉ
G. S. CATTARUZZI2, FABIANO V. IORI9 ,10 , ARIEL M. MARTINE11, ALBERTO B. CARVALHO2, LUIZ E. ANELLI12, MARCELO A.
FERNANDES3, AND HUSSAM ZAHER2
1Programa de Pós-Graduação em Zoologia, Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão (Travessa 14) 321, 05508-
090 São Paul o, SP, Brazil. brunonavarro@alumni.usp.br
2Laboratório de Paleontol ogia e Herpetologia, Museu de Zoologia, Universidade de São Paulo, Avenida Nazaré 481, 04263-0 00 São Paulo, SP, Brazil.
andrecattaruzzi@gmail.com; albertbc3@gmail.com; hussam.zaher@gmail.com
3Laboratório de Paleoecologia e Paleoicnologia, Departamento de Ecologia e Biologia Evolutiva, Universidade Federal de São Carlos, Rodovia Washington Luís (SP-310)
km 235, 13565 -905 São Carlos, SP, Brazil. marcelicno@yahoo.com.br
4Departamento de Geologia, Universidade Federal do Rio Grande do Norte, Rua das Engen harias s/n, Lagoa Nova, 59078-970 N atal, RN, Brazil.
alinemghilardi1@gmail.com
5Institute of Geosciences , University of Campinas, Rua Carlos Gomes 250, 13083-855 Campinas, SP, Brazil. aureliano.tito@gmail.com
6Museum für Naturkunde, L eibniz-Institut für Evolutions-und Biodiversitätsforschung, Invalidenst raße 43, 10115 Berlin, Germany. diezdiaz.veronica@gmail.com
7Institut für Biologie, H umboldt Universität, Invalidenstraße 42, 10117 Berlin, Germany.
8Laboratório de Sistemática e Tafonomia de Répteis Fósseis, Departamento de Geologia e Paleontologia, Museu Nacional, Universid ade Federal do Rio de Janeiro
s/n, 20940-0 40 Rio de Janeiro, RJ, Brazil. kamila.bandeira@mn.ufrj.br
9Museu de Paleontologia “ Prof. Antônio Celso de Arruda Campos”, Centro de Artes, Pra ça do Centenário, 15910-000 Monte Alto, SP, Bra zil. biano.iori@gmail.com
10Museu de Paleontologia “Pedro Candolo”, Estação Cultura, Praça Farmac êutico Bruno Garisto, 15890-000 Uchoa, SP, Braz il.
11Centro de Ciências Human as e da Educação, Universidade Estadual do Nort e do Paraná, Rua Padre de Melo 1200, 86400-000 Jacarezinho, PR, Brazil.
arielmilanimartine@gmail.com
12Depart amento de Geologia Sedimentar e Ambiental, Instituto de Geociências, Universidade de São Paulo, Rua do Lago, 562, 05508-080 São Paulo, SP, Brazil.
anelli@usp.br
Abstract.Titanosaurian sauropods are known to exhibit remarkable body size disparity, with some taxa famed for nearing the zenith of
terrestrial vertebrate body size. Here, we describe a new titanosaurian – Ibirania parva gen. et sp. nov. – from the Upper Cretaceous (Santonian–
Campanian) São José do Rio Preto Formation of Bauru Basin, in which represents one of the smallest sauropods known to date. The new taxon
is diagnosed by seven autapomorphies and had an estimated body length of 5.7 m. Histological and μCT scan analyses showed that this new
taxon is represented by skeletally mature individuals, which had attained somatic maturity prior to death. Phylogenetic analyses recovered
the new taxon deeply nested within Saltasaurinae, a clade previously known by small-sized forms. Ibirania parva gen. et sp. nov. brings new
information indicating that the body size reduction in some titanosaurians could be driven by recurrent ecophysiographical settings, present
in South America prior to the diversity peak attained by the group during the Campanian–Maastrichtian.
Key words. Bauru Basin. Growth Patterns. Histology. Nanism. Saltasauridae. São José do Rio Preto Formation.
Resumen. UN NUEVO TITANOSAURIO ENANO (DINOSAURIA: SAUROPODA) DEL CRETÁCICO SUPERIOR DE BRASIL. Los saurópodos
titanosaurios son conocidos por mostrar una notable disparidad de tamaño corporal, con algunos taxones famosos por acercarse al cenit del
tamaño corporal de un vertebrado terrestre. En este trabajo se describe un nuevo titanosaurio – Ibirania parva gen. et sp. nov. – del Cretácico
Superior (Santoniano–Campaniano) de la Formación São José do Rio Preto de la Cuenca Bauru, el cual representa uno de los saurópodos más
pequeños conocidos hasta la fecha. El nuevo taxón se puede diagnosticar gracias a siete autapomorfías y tenía una longitud corporal estimada
de 5.7 m. Los análisis histológicos y de microtomografía computarizada muestran que este nuevo taxón está representado por individuos
esqueléticamente maduros, que habrían alcanzado la madurez somática antes de la muerte. Los análisis filogenéticos han recuperado la
inclusión del nuevo taxón dentro de Saltasaurinae, un clado previamente conocido por formas de pequeño tamaño. Ibirania parva gen. et sp. nov.
arroja nueva información indicando que la disminución del tamaño corporal en algunos titanosaurios podría estar impulsado por escenarios
ecofisiográficos recurrentes, presentes en América del Sur antes del pico de diversidad alcanzado por el grupo durante el Campaniano–
Maastrichtiano.
Palabras clave. Cuenca Bauru. Patrones de crecimiento. Histología. Enanismo. Saltasauridae. Formación São José do Rio Preto.
AMEGHINIANA - 2022 - Volume 59 (5): 317–354 ARTICLES
ISSN 0002-7014

AMEGHINIANA - 2022 - Volume 59 (5): 317–354
318
TITANOSAURIA is a clade of neosauropods with a remarkable
diversity and worldwide distribution (Curry Rogers, 2005;
Wilson, 2006b; García et al., 2015; González Riga et al.,
2019). They are known to exhibit conspicuous body size dis-
parity marked by the occurrence of giant (e.g., Bonaparte &
Coria, 1993; Novas et al., 2005; Lacovara et al., 2014;
González Riga et al., 2016; Carballido et al., 2017) and nanoid
taxa (e.g., Stein et al., 2010; Klein et al., 2012; Díez-Díaz et al.,
2013b; Curry Rogers & Kulik, 2018; Díez-Díaz et al., 2018).
Titanosaurians represent the most typical large-bodied
herbivorous faunal component in the Late Cretaceous bio-
tas from the southern continents (Powell, 2003; Upchurch
et al., 2004; Tomaselli et al., 2021). Nonetheless, they are
also present in Laurasia, with some forms from the Early
Cretaceous (Dal Sasso et al., 2016; Averianov & Skutschas,
2017; Averianov & Efimov, 2018; Mannion et al., 2019).
Titanosaurian fossils from Brazil have been known since
the late nineteenth century (Derby, 1895; Woodward, 1910;
Pacheco, 1913; Huene, 1931). Most specimens were recov-
ered in the northwestern region of the São Paulo State and
within the “Triângulo Mineiro” region of the Minas Gerais
State. Both regions encompass the Upper Cretaceous
continental deposits of the Bauru Basin (Batezelli, 2015;
Fernandes & Ribeiro, 2015; Menegazzo et al., 2016) in
which, alongside notosuchians, titanosaurians are the most
common vertebrate occurrences (Santucci & Bertini, 2001;
Pol et al., 2014; Bandeira et al., 2018). Ten titanosaur taxa
have been recognized in these strata until now (see Gil et al.,
2020) and, beyond the named forms, the Bauru Basin ti-
tanosaur record also includes: isolated and associated
appendicular and axial remains (e.g., Campos & Kellner,
1999; Santucci & Bertini, 2001; Santucci, 2002; Azevedo et
al., 2007; Lopes & Buchmann, 2008; Silva Jr et al., 2017),
isolated teeth (Candeiro et al., 2006), few cranial bones
(Martinelli et al., 2015), and eggs and eggshells assigned to
Megaloolithidae and Faveoolithidae oofamilies (Magalhães-
Ribeiro, 2002; Grellet-Tinner & Zaher, 2007). Most of these
finds lack a more specific taxonomic assessment (e.g.,
Bertini et al., 2001; Santucci, 2008), hampering major asso-
ciations between axial and appendicular morphotypes.
Another particularity about the titanosaurian fauna
from the Bauru Basin is the small body size displayed by
most of the described species. The Bauru Basin titanosaurians
(e.g., Gondwanatitan faustoi,Trigonosaurus pricei,Brasilotitan
nemophagus) were relatively smaller than other forms re-
ported from coeval localities, usually displaying sizes similar to
found in insular nanoid taxa. Even if some taxa, such as
Arrudatitan maximus, Uberabatitan ribeiroi, and Austroposeidon
magnificus, are represented by large-sized individuals
(20–25 m in length; Bandeira et al., 2016; Silva Jr et al.,
2019, 2021), most of Bauru Basin titanosaur specimens ex-
hibit small to median sizes, ranging between 8–12 m in
body length (Kellner & Azevedo, 1999; Campos et al., 2005;
Kellner et al., 2005; Machado et al., 2013). For example, none
of the known taxa reached the large sizes of their contem-
porary Argentinian species, such as Puertasaurus reuili,
Dreadnougthus schrani, and Notocolossus gonzalezparejasi
(Novas et al., 2005; Lacovara et al., 2014; González Riga et
al., 2016). This pattern raises interesting questions about
the titanosaurian fauna from Bauru Basin, especially when
compared with other correlated Gondwanan occurrences: (i)
was nanism triggered by the environmental stress that pre-
vailed in the region during the end of the Cretaceous? or (ii)
was nanism related to a taphonomical bias? (see Bandeira et
al., 2018). No hypotheses have been previously proposed to
explain this singular pattern.
Here we describe a new titanosaurian taxon from the
Upper Cretaceous (Santonian–Campanian) São José do Rio
Preto Formation. The new taxon is represented by associ-
ated axial and appendicular remains recovered in a single
outcrop located at Sítio dos Irmãos Garcia, in Vila Ventura,
Ibirá Municipality, in northeastern São Paulo State, Brazil
(Fig. 1). This new taxon not only represents one of the
smallest sauropods described to-date but, according to our
expanded phylogenetic analysis, also represents to the first
unequivocal saltasaurine titanosaurian reported for Brazil.
We performed a histological analysis to assess growth pat-
terns that could explain the putative occurrence of a nanoid
taxon outside typical insular habitats. We further discuss if
such pattern is driven by phylogenetic trends, paleoecologi-
cal dynamics, or corresponds to a response to the ecophysio-
graphic settings represented in the Upper Cretaceous of the
Bauru Basin.
Institutional abbreviations. BIBE, Big Bend National Park,
Texas, USA; CPPLIP, Complexo Paleontológico de Peirópolis
Llewellyn Ivor Price, Uberaba, Brazil; DGM, Departamento de
Geologia e Mineralogia, Companhia de Pesquisa de Recursos
Minerais, Rio de Janeiro, Brazil; INPC, Instituto Nacional de

NAVARRO ET AL.: A NANOID TITANOSAUR FROM BRAZIL
319
Patrimonio Cultural, Loja, Ecuador; LPP, Laboratório de
Paleoecologia e Paleoicnologia, Universidade Federal de São
Carlos, Brazil; MACN, Museo Argentino de Ciencias Naturales
Bernardino Rivadavia, Buenos Aires, Argentina; MAL, Malawi
Department of Antiquities, Lilongwe and Nguludi, Malawi;
MAU, Museo Municipal Argentino Urquiza, Rincón de los
Figure 1. Geographic and geological context of Bauru Basin (modified from Delcourt & Iori, 2018). 1, Bauru Basin deposits in the South America,
which the red outline represents the São Paulo State; 2, distribution map and stratigraphic hierarchy adopted in this study for the Bauru Basin
units at the São Paulo State (modified from Menegazzo et al., 2016). The red square denotes the region that has collected the specimens
studied here. Asterisks mark the subsurface units; 3, distribution map of São José do Rio Preto Formation in the north-western region of the
São Paulo State. The red arrow shows the location of the outcrop that has yielded the Ibirania parva gen. et sp. nov. specimens. Yellow lines
represent federal (BR) and state (SP) highways.

Sauces, Argentina; MCNA, Museo de Ciencias Naturales de
Álava, Vitoria-Gasteiz, Spain; MCS, Museo de Cinco Saltos,
Cinco Saltos, Argentina; MCT, Museu de Ciências da Terra,
Companhia de Pesquisa de Recursos Minerais, Rio de Janeiro,
Brazil; MLP, Museo de La Plata, La Plata, Argentina; MN,
Museu Nacional, Universidade Federal do Rio de Janeiro,
Brazil; MPCA, Museo Provincial Carlos Ameghino, Cipolletti,
Argentina; MPMA, Museu de Paleontologia Prof. Antonio
Celso de Arruda Campos, Monte Alto, Brazil; MPPC, Museu
de Paleontologia Pedro Candolo, Uchoa, Brazil; MZSP,
Museu de Zoologia, Universidade de São Paulo, São Paulo,
Brazil; NHM, Natural History Museum, London, United
Kingdom; PVL, Instituto Miguel Lillo, San Miguel de Tucumán,
Argentina; UTPL, Universidad Técnica Particular de Loja,
Ecuador; YM, Yamana locality collection, Loja, Ecuador.
Anatomical abbreviations.ACDL, anterior centrodiapophyseal
lamina; CDF, centrodiapophyseal fossa; CPOL, centropos-
tzygapophyseal lamina; CPRL, centroprezygapophyseal
lamina; EPRL, epipophyseal-prezygapophyseal lamina; lat.
CPOL, lateral centropostzygapophyseal lamina; lat. CPRL,
lateral centroprezygapophyseal lamina; lat. SPOL, lateral
spinopostzygapophyseal lamina; med. CPOL, medial cen-
tropostzygapophyseal lamina; med. CPRL, medial centro-
prezygapophyseal lamina; med. SPOL, medial spinopostzy-
gapophyseal lamina; PACDF, parapophyseal-centrodiapop-
hyseal fossa; PCDL, posterior centrodiapophyseal lamina;
PCPL, posterior centroparapophyseal lamina; POCDF, pos-
terior centrodiapophyseal fossa; PODL, postzygodiapophy-
seal lamina; POSF, postspinal fossa; POSL, postspinal
lamina; PPDL, paradiapophyseal lamina; PRDF, prezygodia-
pophyseal fossa; PRDL, prezygodiapophyseal lamina; PRPL,
prezygoparapophyseal lamina; PRSDF, prezygapophyseal-
spinodiapophyseal fossa; PRPADF, prezygapophyseal-pa-
radiapophyseal fossa; PRSF, prespinal fossa; PRSL,
prespinal lamina; SPDL, spinodiapophyseal lamina; SPOL,
spinopostzygapophyseal lamina; SPRL, spinoprezygapop-
hyseal lamina; TPOF, intrapostzygapophyseal fossa; TPOL,
intrapostzygapophyseal lamina; TPRL, intraprezygapophy-
seal lamina.
MATERIALS AND METHODS
Materials
At least four specimens of the new taxon are known
from a single horizon. Both axial and appendicular remains
are preserved. Axial remains of the new taxon comprise
fragmentary-to-moderately preserved elements. The most
complete elements have their approximate position in the
axial column established primarily by the position of zy-
gapophyses, by the elevation of parapophyses relative to
the diapophyses, and the neural spine inclination and de-
velopment when preserved (Gallina, 2011).
The appendicular elements associated with the new
taxon consist of a fragmentary right radius and ulna, the
distal half of a right metacarpal, diaphyseal fragments of a
right and a nearly fully preserved left fibula, and an almost
complete left metatarsal. Intense pre- and post-diage-
netic weathering obliterated several morphological traits,
which hampered comparisons. Nevertheless, the specimens
were useful to estimate limb heights and to histological
sampling.
We compared the new taxon primarily with the type
specimens of Brazilian titanosaurians that share overlap-
ping elements, including Gondwanatitan faustoi (MN 4111-
V), Baurutitan britoi (MCT 1490-R), Trigonosaurus pricei
(MCT 1488-R, 1719-R), Maxakalisaurus topai (MN 5013-V),
Uberabatitan ribeiroi (CPPLIP-0494, 1019, 1032, 1068,
1077, 1107, 1108), and Tapuiasaurus macedoi (MZSP-PV
807). Additional comparisons were made with a set of un-
described titanosaurian specimens from the Bauru Basin
(DGM 775-R; MCT 1487-R, 1616-R, 1619-R, 1621-R; CP-
PLIP 0036, 0037, 0110, 0111, 0361, 0458) and with the
closely related taxa Neuquensaurus australis (MCS-Pv 5),
Saltasaurus loricatus (PVL 4017), Rocasaurus muniozi (MPCA-
Pv 46, 858, 859, 860), Bonatitan reigi (MACN-Pv RN 821,
1061), Yamanasaurus lojaensis (YM-UTPL-002, YM-INPC-
014–017), and an unnamed from Angostura Colorada
Formation (MACN-Pv RN 233). Further comparisons were
extended to Malawisaurus dixeyi (MAL-180, 239, 243, 245,
278, 280, 283), Overosaurus paradasorum (MAU-Pv-CO-
439), and some small-sized titanosaurian taxa from Europe,
such as Magyarosaurus dacus (NHM-R.3861 and R.4896)
and Lirainosaurus astibiae (MCNA 7442, 7443, 7445, 1882,
2207, 2208, 2211, 7451, 7452, 7454, 7455, 7457, 7458,
8605–8607, 9647, 13388, 13851, 13853, 13854, 13857,
14435–14455). First-hand observations on these speci-
mens were conducted by BAN, KLNB, and VDD (see Supple-
mentary Online Information).
AMEGHINIANA - 2022 - Volume 59 (5): 317–354
320

Methods
Computed Tomography (CT) Imagery. The holotypic poste-
rior dorsal vertebra (LPP-PV-0200) was tomographed using
a Philips Diamond Select Brilliance CT 16-slice medical
scanner with more than 200 slices and a voxel size of 0.75
mm at the HU-UFSCar. Acceleration voltage varied between
90 and 120 kV in a current of 367 mA. We followed the
methodology applied by Aureliano et al. (2020) to process
the data and generate the three-dimensional reconstruc-
tion with the software 3D Slicer © v4.10 (Fedorov et al.,
2012) and CloudCompare © v2.9.1.
The µCT-scanning procedures applied to LPP-PV-200
were performed on the Phoenix v|tome|x M 300 (General
Electric Measurement & Control Solutions, Wunstorf,
Germany). This equipment is a 300-kV μ-focus X-ray source
installed at the Laboratório de Microtomografia of the
Museu de Zoologia, Universidade de São Paulo, Brazil. X-ray
projection images were set at 333 ms of time of exposure
per image, in one slow 360 degrees stepwise rotation of
the sample, with 4000 images, voltage 220 kV, current 250
μA, and voxel size resolution 146 μm. A beam hardening
correction filter was used to reduce artifacts, using the
factor of six (values varying from zero to 10).
Data processing was executed using a high-performed
workstation model HP Z820 with an eight-core Intel Xeon ©
2.20GHz, with 128 GB of RAM memory, run on Microsoft
Windows 7 Ultimate © 64-bit operating system. The recon-
struction of acquired raw data was performed using the GE
system-supplied software phoenix datos|x reconstruction
v. 2.3.0 (General Electric Measurement & Control Solutions,
Wunstorf, Germany). Three-dimensional editions as well as
the analysis of the reconstructed data were performed
using the software VGStudio MAX © V2.2.3 64 bits (Volume
Graphics GmbH, Heidelberg, Germany).
Thin Section Sampling. Samples were taken from the holo-
type (LPP-PV-0202) and a referred specimen (LPP-PV-
0043) of Ibirania parva, n. gen., n. sp., to evaluate growth
patterns. Specimens were tomographed prior to sectioning.
We used Epoxiglass © 1.504 resin to embed the fossil, fol-
lowing standard procedures to prepare the thin sections
(sensu Lamm, 2013). Samples were ground to a thickness
of approximately 40 to 60 µm. Thin sections were observed
and photographed using a petrographic ZEISS © Axioscope
microscope with an AxioCam MRc 5 camera attached and
imaging by the software ZEISS © Application Suite v. 4.4.
Samples measurements were taken through ImageJ v.1.8.
The Histological Ontogenetic Stage (HOS) of the specimen
was established and comparisons were made with the pub-
lished literature (e.g., Klein & Sander, 2008; Stein et al., 2010;
Company, 2011; Klein et al., 2012; Curry Rogers et al., 2016;
Díez-Díaz et al., 2018). Furthermore, we also applied the
‘three-front model’ suggested by Mitchell and Sander
(2014), as an additional approach to infer ontogenetic ma-
turity in these specimens.
Data archiving. High-resolution µCT-scan reconstructions
and thin section images of specimens used in this study are
available at MorphoBank (https://www.morphobank.org),
project ID 4184.
Measurements. Axial and appendicular materials were
measured using digital calipers and measuring tape. Verte-
bral measurements included total height, centrum length,
width, and height, the height of the neural arch and spine,
as well as the Elongation Index (EI). The EI represents the
centrum length divided by the mean average value of the
posterior mediolateral width and dorsoventral height.
Measurements of all axial materials are available in Table 1.
The Eccentricity Index (ECI) was calculated for appendicular
bones, corresponding to the mid-shaft mediolateral breadth
divided by the anteroposterior breadth (Wilson & Carrano,
1999). The Robustness Index (RI) has been calculated as
the average of the greatest widths, as preserved, of the
proximal and distal ends, and the mid-shaft divided by
the preserved length of the element in question (Wilson &
Upchurch, 2003). Measurements of all appendicular mate-
rials are available in Table 2.
Anatomical and Directional Terminology. We used for
anatomical structures and their orientations the traditional
“Romerian” terminology instead of the veterinarian and
avian alternatives, as proposed by Wilson (2006a). For the
identification and designation of vertebral laminae and fos-
sae we follow the landmark-based scheme proposed by
Wilson (1999, 2012) and Wilson et al. (2011), respectively.
For internal pneumatic bony tissues, we follow the nomen-
clature proposed by Wedel et al. (2000) and Wedel (2003,
2007).
Phylogenetic Analysis. We investigated the phylogenetic
relationships of the new taxon within Titanosauria using the
recently published dataset of Carballido et al. (2017) as
NAVARRO ET AL.: A NANOID TITANOSAUR FROM BRAZIL
321

modified by Filippi et al. (2019), Carballido et al. (2020), and
Hechenleitner et al. (2020). We further expanded both taxon
sampling and character sets based on new information
available, and scoring modifications based on our new ob-
servations. The complete list of modifications, scorings, and
support analyses are provided in the Supplementary Online
Information. Character scorings were made on Mesquite
v3.61 (Maddison & Maddison, 2011) and exported in both
.NEX and .TNT formats.
The resulting dataset encompassed 114 taxa and 435
characters. Characters scored included 88 from the skull, 20
from the mandible, 14 from teeth, 37 from the cervical se-
ries, 64 from the dorsal series, four from the cervical and
dorsal ribs, six from the sacral vertebrae, 62 from the caudal
series, six from the chevrons, 26 from the pectoral girdle,
29 from the forelimb, 25 from the pelvic girdle, 53 from the
hind limb, and one from the dermal skeleton. We followed
Carballido et al. (2017) in treating 24 multistate characters
as ordered (14, 61, 100, 102, 109, 115, 127, 132, 135, 136,
166, 179, 195, 256, 259, 276, 277, 278, 279, 299, 303, 346,
352, 354). Taxon sampling included 64 terminal taxa in the
outgroup and 50 terminal taxa in the ingroup. Unstable
taxa were detected using the ‘iterpcr’ method in TNT (Pol &
Escapa, 2009). This allowed to recover the following eight
highly unstable rogue taxa, all with fragmentary mor-
phologies: Isanosaurus attavipachi,Rayososaurus agrioensis,
Lusotitan atalaiensis,Padillasaurus leivaensis,Malarguesaurus
florenciae,Quetecsaurus rusconii,Drusilasaura deseadensis
and Garrigatitan meridionalis. They were subsequently re-
moved from the matrix, resulting in the present dataset
used in this study (i.e., 435 chars for 106 terminals).
The reduced dataset was analyzed using equally
weighted parsimony in TNT v1.5 (Goloboff et al., 2008). We
conducted the analysis with the “New Technology Search”,
using the command “xmult=hits100”. Under this command,
Sectorial Search, Ratchet, Drift, and Tree Fusing algorithms
are applied together with the traditional search procedures,
such as Wagner Trees, Tree Branch Reconnection (TBR)
and Subtree-Pruning-Regrafting algorithms, to find the
Minimum Length Trees (MLTs). A final round of TBR branch
swapping was applied to the optimal trees obtained at the
end of the replicates by using the command “bb”, to find all
AMEGHINIANA - 2022 - Volume 59 (5): 317–354
322
TABLE 1. Selected measurements of axial bones of Ibirania parva gen. et sp. nov. in millimeters (mm).
Material Specimen Acronym TH CL CW CH NAH NSH EI
Middle cervical centrum Referred MPPC 02-012 - 251* 132* 136* - - 0,53
Posteriormost cervical vertebra Referred MPMA 08-0049/02 171* 191* 106* 63* 106* - 0,44
Anteriormost dorsal vertebra Referred MPMA 08-0050/01 194* 200* 121* 88* 129* 93* 0,52
Anterior dorsal neural arch Referred MPPC 02-013 - - - - 120* - -
Anterior dorsal neural arch Referred MPPC 00-023 - - - - 79* - -
Middle dorsal centrum Referred MPPC 02-005 - 203* 133* 131* - - 0,65
Posterior dorsal vertebra Holotype LPP-PV-0200 271 175* 85* 93* 186 116 0,51
First caudal centrum Holotype LPP-PV-0204 - 138* 53* 72* - - 0,45
Middle caudal vertebra Referred MPMA 08-0060/07 116 89 62 70 46* 35* 0,74
Middle caudal neural arch Holotype LPP-PV-0206 - - - - 70* 67* -
Posterior caudal centrum Holotype LPP-PV-0205 - 54* 33* 32 - - 0,60
An asterisk (*) marks the measurements based only on preserved portions, while a dash (-) denotes when the region is not preserved or indi-
cates measurements that could not be taken. Abbreviations: TH, Total Height; CL, Centrum Length; CW, Centrum Width; CH, Centrum Height;
EI, Elongation Index; NAH, Neural Arch Height (measured from dorsal surface of the centrum to the top of neural spine); NSH, Neural Spine
Height (measured from the intrapostzygapophyseal lamina to the top of neural spine).

the Most Parsimonious Trees (MPTs). A maximum of
100000 MPTs was set to be saved in memory. For the con-
struction of a strict consensus tree, zero length branches
were collapsed (collapsing rule 3) if they lacked support
under any of the most parsimonious reconstructions (Fig. 1
in Supplementary Online Information).
Node supports for the MPT’s were calculated using
Bootstrap and Jackknife (Felsenstein, 1985), and Bremer
(Decay Index; Bremer, 1994). Resampling support analyses
consisted in 1000 pseudoreplicates in TNT with the same
tree search strategy employed for the parsimony analysis,
in which the resulting trees were summarized through ab-
solute and GC frequencies. Bremer support was calculated
using the TNT script “bremsup.run” that combines heuristic
searches of suboptimal trees allied to tree searches under
negative constraints (Fig. 2 in Supplementary Online Infor-
mation).
The obtained topologies were processed in FigTree v1.4.2
and the R v4.0.3 (available at https://www.r-project.org/).
The strict consensus was temporally scaled in the R soft-
ware, using the “ape”, “strap” and “phytools” packages, and
followed the method described by Ruta et al. (2006) (see Fig.
3 in Supplementary Online Information).
Phylogenetic Definitions. The phylogenetic definitions used
in this study are summarized in the Supplementary Online
Information. Newly proposed clade definitions were regis-
tered at RegNum platform (https://www.phyloregnum.org/)
of the International Code of Phylogenetic Nomenclature
(PhyloCode; Cantino & de Queiroz, 2020). Following article
6, recommendation 6.1A from the Phylonyms (de Queiroz
et al., 2020), all clades established under this code are itali-
cized (see Supplementary Online Information).
SYSTEMATIC PALEONTOLOGY
DINOSAURIA Owen, 1842
SAUROPODA Marsh, 1878
NEOSAUROPODA Bonaparte, 1986
MACRONARIA Wilson & Sereno, 1998
TITANOSAURIA Bonaparte & Coria, 1993
LITHOSTROTIA Upchurch, Barrett & Dodson, 2004
EUTITANOSAURIA Sanz, Powell, Le Loeuff, Martínez &
Pereda Suberbiola, 1999
SALTASAUROIDEA Powell, 1992
SALTASAURIDAE Powell, 1992
SALTASAURINAE Powell, 1992
Ibirania gen. nov.
LSID urn:lsid:zoobank.org:act:1E4BCAB6-7D37-4199-9667-1BBA61489EEF
Type species. Ibirania parva sp. nov. from the late Santonian to early
Campanian (Upper Cretaceous) of São José do Rio Preto Formation,
Bauru Basin at Ibirá Municipality, São Paulo State, Brazil (Fig. 2).
NAVARRO ET AL.: A NANOID TITANOSAUR FROM BRAZIL
323
TABLE 2. Selected measurements of appendicular bones of Ibirania parva gen. et sp. nov. in millimeters (mm).
Material Side Specimen Acronym TH APB MLB PW DW MSC ECI RI
Radius Right Holotype LPP-PV-0203 256* 56 33 - 71* 140 0,59 0,25
Ulna Right Holotype LPP-PV-0202 223* 66 40 95* 78* 130 0,61 0,36
Metacarpal Right Holotype LPP-PV-0201 112* 29 27 - 47 32 0,93 0,34
Metatarsal Left Holotype LPP-PV-0207 108 38 20 63 51 76 0,53 0,47
Fibula Right Referred LPP-PV-0043 139* 65 48 - - 167 0,74 -
Fibula Left Referred MPMA 09-0001/99 434* 66 48 112* 86* 178 0,73 0,20
An asterisk (*) marks the measurements based only on preserved portions, while a dash (-) denotes when the region is not preserved or indi-
cates measurements that could not be taken. Abbreviations: TH, Total Length; APB, Anteroposterior Breadth; MLB, Mediolateral Breadth; PW,
Proximal Width; DW, Distal Width; MSC, Mid-Shaft Circumference; ECI, Eccentricity Index; RI, Robustness Index.

Diagnosis. As for type and only known species, by monotypy.
Ibirania parva sp. nov.
Figures 1–13; Tables 1, 2
LSID urn:lsid:zoobank.org:act:3E8A5EC8-0E0B-4351-A454-02746D2ECC1A
Etymology. The generic epithet is a combination of the
name “Ibirá”—the municipality in which the specimens
were found—with “ania”, a modified form of the Greek word
“plania” (meaning “wander”). The name Ibirá is a Portuguese
derivative from the Tupi word “ybyrá”, which means “tree”
or “wood.” Thus, the name of this new genus, means “Ibirá
wanderer” or even “tree wanderer” in allusion to its browser
feeding behavior. The specific epithet “parva” – a feminine
substantive – is derived from the Latin word “parvus,” which
means small or little, in reference to the nanism exhibited
by this form.
Holotype. The holotype of Ibirania parva consists of disar-
ticulated but associated postcranial remains of a single in-
dividual (Fig. 3), including: a moderately preserved posterior
dorsal vertebra (LPP-PV-0200), partial anterior (LPP-PV-
0204) and posterior caudal centra (LPP-PV-0205), partial
neural arch of a mid-caudal vertebra (LPP-PV-0206), frag-
mentary radius (LPP-PV-0203) and ulna (LPP-PV-0202),
the distal half of a metacarpal (LPP-PV-0201), and a nearly
complete metatarsal (LPP-PV-0207). All materials are re-
ferred to the same individual because they were found on
the same layer and in close association, lacking overlapping
elements (see Figs. 4–5 in Supplementary Online Informa-
tion). In addition, all the bones exhibit similar diagenetic
features (e.g., ferruginous impregnations and moderate
oxidation), compatible size (reconstructed size of the radius
367 mm, ulna 364 mm, and metacarpal 242 mm), and they
are the only titanosaurian material found at this stratum.
Besides the proximity of the bone remains, the forelimb ma-
terials are all from the right side and their taphonomic sig-
nature (e.g., lacking most of the proximal portions) support
the view that these pertained to the same individual.
Referred material. Additional individuals (Fig. 3) recovered
from adjacent outcrops are assigned as referred specimens
of Ibirania parva. They consist of a fragmentary cervical cen-
trum (MPPC 02-012), a nearly preserved posteriormost cer-
vical vertebra (MPMA 08-0049/02), a partial anterior dorsal
vertebra (MPMA 08-0050/01), two partial neural arches of
probable anterior dorsal vertebrae (MPPC 02-013 and
MPPC 00-023), a mid-dorsal centra (MPPC 02-005), a com-
plete mid-caudal vertebra (MPMA 08-0060/07), diaphyseal
fragments of a fibula (LPP-PV-0043), and a nearly com-
plete fibula (MPMA 09-0001/99). These specimens are
associated with this taxon because they share the autapo-
morphies that diagnose the holotype, similar diagenetic
features, and were found close to this specimen at the same
horizon (see Figs. 4 and 6–8 in Supplementary Online Infor-
mation).
Repositories. The holotype (LPP-PV-0200–0207), referred
specimen (LPP-PV-0043), and histological samples are de-
posited at the Laboratório de Paleoecologia e Paleoicnologia
(LPP) of the Departamento de Ecologia e Biologia Evolutiva,
Universidade Federal de São Carlos (UFSCar), São Carlos
Municipality, São Paulo State, Brazil. The remaining refer-
red specimens (MPMA 08-0049/01–02, 08-0060/07, 09-
0001/99; MPPC 00-023, 02-005, 02-012, 02-013) are
deposited in two institutions: Museu de Paleontologia de
Monte Alto ‘Professor Antônio Celso de Arruda Campos’
(MPMA), Monte Alto Municipality, and Museu de Paleonto-
logia ‘Pedro Candolo’ (MPPC), Uchoa Municipality, São Paulo
State.
Geographic occurrence. The holotype was collected in a
single outcrop (Figs. 1–2; see Figs. 4–5 in Supplementary
Online Information), located at Sítio dos Irmãos Garcia
(Garcia Brothers Farm), near the Washington Luis State
Highway (SP-310) in Vila Ventura, Ibirá Municipality, north-
eastern São Paulo State, Brazil. The referred specimens
were collected in coeval levels (altimetric height equals 493
m) from outcrops around Vila Ventura District. GPS coordi-
nates of these localities are deposited in their respective
collections (LPP, MPMA, and MPPC) and are available upon
request.
Stratigraphic occurrence. All individuals assigned to Ibirania
parva were collected in brownish to pinkish layers of mas-
sive conglomeratic sandstones (Fig. 2). These facies are
characterized by trough-cross bedding stratification and
high carbonate cementation, with minor intercalation of
mudstone lenses and shale pellets, typical of the São José
do Rio Preto Formation (sensu Fernandes & Ribeiro, 2015;
Menegazzo et al., 2016; see Fig. 4 in Supplementary Online
Information) and may comprise the lower level from this
unit based on their stratigraphic correlations. Previous mi-
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324

cropaleontological and correlated radiometric data constrain
these horizons in a late Santonian to early Campanian age
(Dias Brito et al., 2001; Castro et al., 2018; see Geological
Settings in the Supplementary Online Information). Isotopic
data suggest an arid to semi-arid paleoenvironment (δ18O =
-5.98 and δ13C = -6.26; Dias Brito et al., 2001).
Diagnosis. Ibirania parva represents a small-sized
saltasaurine titanosaurian that can be distinguished from
all other titanosaurian taxa by the following autapomor-
phies: (1) dorsal vertebrae with thick (almost “rod-shaped”)
PRSL bearing an additional prominent crest at mid-height;
(2) dorsal vertebrae with thick SPRL that surpasses half
of PRSL height. In the anterior elements the SPRL extends
parallelly to the PRSL, whereas in the posterior ones they
merge in the lateral surface of PRSL, not extending beyond
their ventral end as a tripartite laminae; (3) posterior dorsal
vertebrae with subparallel anterior SPDL and posterior SPDL,
with the medial extremity of posterior SPDL projecting
dorsally beyond the level of the anterior lamina, and form-
ing a ventral contact with incipient aliform processes; (4)
single CPRL in posterior dorsal vertebrae with expanded
dorsal and ventral extremities, forming a thin anterolateral
rim to the CPRF; (5) posterior dorsal vertebrae with a SPOL
bearing two rami (med. SPOL and lat. SPOL), with the lat-
eral one being forked due to the presence of an enlarged
pneumatic foramen, forming two branches, and the medial
one forming part of a median posterior ridge; (6) mid-caudal
centra with a ventral hollow, but lacking longitudinal bony
NAVARRO ET AL.: A NANOID TITANOSAUR FROM BRAZIL
325
Figure 2. Fossil-bearing site at Vila Ventura District, Ibirá Municipality, São Paulo State. 1, general view of the outcrops in a pasture area and
its various rock levels. The yellow star indicates the exact point where the holotypic specimen of Ibirania parva gen. et sp. nov. was recovered.
The referred specimens were collected at the same stratigraphic level; 2, rock section showing all lithofacies occurring in these outcrops; 3,
transition from Facies B2 (massive sandstones) to Facies A (conglomeratic sandstones) and its non-concordant contact; 4, detail of Facies A
(conglomeratic sandstones).

septa or ventrolateral ridges; (7) ulna bearing a distinctive
muscular pit on the posteromedial surface of its distal half.
Our phylogenetic analysis further recovered the follow-
ing additional potential autapomorphies: presence of the
SPRL on entirely dorsal series (Char. 162 and 163: 0→1);
divided CPOL on mid- and posterior dorsal neural arches
(Char. 191: 0→1); mid- and posterior dorsal neural arches
lacking the ACPL and PRPL (Chars. 192 and 193: 1→0);
ventral contact of SPDL and SPOL in mid- and posterior
dorsal neural arches (Chars. 203: 1→0); a med. SPOL present
and forming part of the median posterior ridge on posterior
dorsal neural arches (Char. 205: 0→1); laminar neural spine
on posterior dorsal neural aches narrower transversely than
anteroposteriorly (Char. 208: 2→0); anterior caudal centra
ventrally convex (Chars. 233: 1→0); incipient ventral exten-
sion of the TPRL, not reaching the aperture of neural canal
(Char. 428: 0→1).
Comparative diagnosis. Ibirania parva can be further distin-
guished from other South American titanosaurians by the
following combination of plesiomorphic and apomorphic
characters. Putative additional autapomorphies are marked
with an asterisk (*). Some characters shared between the
holotype and referred specimens are discussed, allowing
the association of both materials as belonging to the same
taxon.
The cervicodorsal vertebrae of Ibirania parva are charac-
terized by their anteroposteriorly elongated centra (Tab. 1).
The posteriormost cervical centrum bears a conspicuous dor-
sal notch in the cotyle, similar to the one found in Europasaurus
holgeri Sander et al., 2006 (Carballido & Sander, 2014) and
Rocasaurus muniozi Salgado & Azpilicueta, 2000. Postzy-
gapophyses of the posteriormost cervical vertebrae bear a
stout “pillar-like” epipophysis but, like in other saltasaurines
(e.g., Roc as au rus muniozi), apparently lack an EPRL, as
present in other titanosaurians such as Uberabatitan ribeiroi
Salgado & Carvalho, 2008 and Brasilotitan nemophagus
Machado et al., 2013 (Salgado & Azpilicueta, 2000; Silva Jr
et al., 2019). Like the posterior dorsal vertebrae, the poste-
riormost cervical vertebrae apparently possess a SPOL that is
divided into two rami (med. SPOL and lat. SPOL) and presents
a large dorsomedial pneumatic foramen in the anterior por-
tion of the POCDF, as in Saltasaurus loricatus Bonaparte &
Powell, 1980 and Rocasaurus muniozi (Zurriaguz & Powell,
2015).
The anterior dorsal vertebrae exhibit tapered and low
neural spines, as in Trigonosaurus pricei Campos et al., 2005,
Overosaurus paradasorum Coria et al., 2013, Pitekunsaurus
macayai Filippi & Garrido, 2008, and Muyelensaurus pecheni
Calvo et al., 2007. However, in contrast to these taxa, the
anterior dorsal vertebrae of Ibirania pa rva bear a well-
developed SPRL and a broad and deeper POSF. The dorsal
vertebrae referred to Ibirania parva possess a thick POSL
along most of the posterior face of the neural spine, unlike
Uberabatitan ribeiroi and Isisaurus colberti Jain & Bandyopad-
hyay, 1997. The anterior and posterior dorsal vertebrae of
Ibirania parva also share a well-developed PODL but lack a
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326
Figure 3. Skeletal reconstruction of Ibirania parva gen. et sp. nov., based on the body proportions of the holotypic specimen. Recovered bone
elements (colored) and missing bones (white) were reconstructed through comparisons with closely related taxa. Color key: orange elements
represent the holotype (LPP-PV-0200 to 0207*); blue elements represent the referred specimens (MPMA 08-0049/02, 08-0050/01, 08-
0060/07, 09-0001/99; MPPC 02-005, 02-012, 00-013, 00-023). The asterisk marks a reversed element for a better visualization. Scale bar
equals 1 m, human silhouette displays 1.8 m.

hyposphene-hypantrum complex and a dorsal notch on the
cotyle. Unlike the posterior dorsal vertebrae, the PRSL and
POSL of Ibirania parva anterior dorsal vertebrae bear smooth
ventral bulges (*).
The posterior dorsal vertebra is characterized by lacking
an ACPL (*), a PRPL (*), and bearing prezygapophyseal ar-
ticular facets that tapers medioventrally (subtriangular in
shape) (*), and sharp postzygapophyseal borders that taper
dorsolaterally (*). Like Trigonosaurus pricei, a pronounced
bulge is present below the TPRL, but in Ibirania parva it is
more beveled anteriorly and pierced by a small foramen. The
PPDL is slender and well-developed, as in Bonatitan reigi
Martinelli & Forasiepi, 2004 and Lirainosaurus astibiae Sanz
et al., 1999 (Díez-Díaz et al., 2013a; Salgado et al., 2015). The
aliform processes are rudimentary and are not formed by
an extension of the SPDL, being more perpendicular in re-
spect to the vertical axis of the neural spine. This condition
differs from some titanosaurians, such as Argentinosaurus
huinculensis Bonaparte & Coria, 1993, Patagotitan mayorum
Carballido et al., 2017, and Saltasaurus loricatus (Zurriaguz &
Powell, 2015).
The lateral aspect of the neural spine is marked by pneu-
matic foramina, with an enlarged foramen present below the
lat. SPOL, like the condition found in Saltasaurus loricatus.A
deep and excavated POCDF is present, ventrally surrounded
by an anterior expansion of the lat. CPOL that connects with
the PCDL, a condition shared with posterior dorsal verte-
brae referred to Malawisaurus dixeyi Jacobs et al. 1993
(Gomani, 2005) and CPPLIP 0494. A large “V-shaped” pneu-
matic foramen in the POCDF is present, as in Saltasaurus
loricatus. Posterior dorsal vertebrae also display a columnar
med. CPOL that is slightly forked on its dorsal portion by a
median groove (*), like the anterior dorsal vertebrae of
Mendozasaurus neguyelap González Riga, 2003 (González
Riga et al., 2018).
The first caudal centrum of Ibirania parva displays a bi-
convex-type articulation as observed in other saltasaurids,
such as Yamanasaurus lojaensis Apesteguía et al., 2020,
Neuquensaurus australis Lydekker, 1893, Alamosaurus
sanjuanensis Gilmore, 1922 (Gilmore, 1946), and Baurutitan
britoi Kellner et al., 2005. The first caudal centrum of Ibirania
parva is anteroposteriorly elongated, differing from the con-
dition present in cf. Antarctosaurus wichmannianus Huene,
1929 and Pellegrinisaurus powelliSalgado, 1996, which exhibit
anteroposteriorly shortened biconvex centra. Pneumaticity in
the caudal series is like Saltasaurus loricatus and Rocasaurus
muniozi, in which the internal somphospondylous tissue
reaches the mid- to posterior elements (Zurriaguz & Cerda,
2017). The mid-caudal neural arches exhibit posterodorsally
inclined neural spines, as in other saltasaurines, lacking the
postzygapophyseal bony processes present in Rinconsaurus
caudamirus Calvo & González Riga, 2003,Muyelensaurus pecheni,
Bonitasaura salgadoi Apesteguía, 2004, and Uberabatitan
ribeiroi (Gallina & Apesteguía, 2015).
The appendicular material of Ibirania parva, although
fragmentary, displays robust profiles (Tab. 2), like other
saltasaurids. The radius appears to expand distally, as in
several macronarians (Upchurch et al., 2015), and the ulna
has a triradiate “D-shaped” cross section on mid-shaft. The
lateral trochanter of the fibula is incipient and vertically
placed (*), differently from other titanosaurians, such as
Laplatasaurus araukanicus Huene, 1929 and Uberabatitan
ribeiroi (Gallina & Otero, 2015).
Ontogenetic assessment. Holotypic and referred specimens
of Ibirania parva are represented by skeletally mature indi-
viduals, based on morphological and osteohistological ap-
proaches. The ontogenetic assessment was established
following the HOS parameters of Klein and Sander (2008)
for long-bone tissue types, and the ‘three-front-model’ of
Mitchell and Sander (2014) for ontogenetic maturity (see
below).
DESCRIPTION AND COMPARISONS
Axial Skeleton
Posteriormost cervical vertebra. Referred posteriormost
cervical vertebra (MPMA 08-0049/02; Fig. 4) is partially
preserved, missing the anterior part of the neural spine,
prezygapophyses, diapophyses, and most of the right side.
The centrum, as preserved, is anteroposteriorly elongated
(Tab. 1) and is distorted obliquely in the left side (Fig. 4.1–
4.4). The condyle is abraded by transport before the com-
plete burial, preserving in the right side only the internal
surface of the pleurocoelic cavity and a small portion of the
parapophysis, which is also visible in the anterior view (Fig.
4.1, 4.2). Laterally, the pleurocoelic cavities are present as
deep fossae without well-defined edges, differing from the
condition present in Saltasaurus loricatus. However, in the
referred mid-to-posterior centrum (MPPC 02-012), it is
NAVARRO ET AL.: A NANOID TITANOSAUR FROM BRAZIL
327

possible to observe a small well-defined pneumatopore on
the left side. Additionally, MPPC 02-012 also preserves
marked striations in the ventral path of the left fossa that
extends laterally (see Fig. 6 in Supplementary Online Infor-
mation), possibly related to the development of insertion
points of diverticula. Internally, the somphospondylous tis-
sue of both cervical elements is arranged into large “honey-
comb-shaped” cells (Fig. 4.5; Fig. 6 in Supplementary Online
Information). The ventral surface of the cervical centrum of
MPMA 08-0049/02, although exhibiting an oblique distor-
tion, is almost flat transversally (Fig. 4.6). Posteriorly and
dorsally, the cotyle bears a well-marked dorsal notch.
The neural arch only preserves a portion of its left side
(Fig. 4.1–4.4), displaying well-developed and thick laminae.
Part of a stout and single CPRL is visible in anterior and
lateral views and is strongly projected anterodorsally. How-
ever, it is not at the same level as the diapophyses as seen
in Saltasaurus loricatus and Neuquensaurus australis (see Fig.
7 in Supplementary Online Information). The anterodorsal
end of the prezygapophysis is not fully preserved, but ap-
parently lacks the posteroventral processes on the lateral
surface. A PRDF is present, exhibiting an “U-shaped” ventral
outline. The extension of PRDF cannot be assessed due to
the fragmentary condition of the dorsal end of the PRDL and
the absence of preserved diapophyses. The left diapophysis,
although not fully preserved, is supported by a thick ACDL
and by a thickened posterior PCDL. The PCDL dorsally
borders a longitudinally elongated and deep CDF, like
Trigonosaurus pricei (see Fig. 7 in Supplementary Online In-
formation). The PODL is damaged but, within the PCDL, de-
limit a deep and ellipsoid shaped POCDF. A tall foramen
pierces the dorsomedial surface of the anterior portion of
POCDF.
The preserved postzygapophysis extends posterolater-
ally to the cotyle edge (Fig. 4.2–4.4). The articular surface is
anteroposteriorly broader than that of the preserved prezy-
gapophysis and, as in Rocasaurus muniozi, the angle of ar-
ticulation is posteroventrally oriented around 30º (see Fig.
7 in Supplementary Online Information). This condition dif-
fers from that in other saltasaurines, such as Neuquensaurus
australis and Saltasaurus loricatus, in which the articular sur-
faces of postzygapophyses are strongly angled, reaching
more than 45º (see Fig. 7 in Supplementary Online Informa-
tion). Dorsally, the postzygapophysis bears a stout and pil-
lar-like epipophysis, but there are no signs of an EPRL, as
in the posterior cervical vertebrae of Saltasaurus loricatus
(PVL 4017-7). In turn, the postzygapophysis is connected to
the preserved left lateral part of the neural spine by thick
SPOL, which is split, as in dorsal elements (see below), into
two segments: the lateral and medial SPOL. The former is
visible only in the lateral aspect, whereas the latter is visi-
ble in both lateral and posterior views and probably contacts
ventromedially with the TPOL. From below, the postzy-
gapophysis is supported by a wide CPOL, which apparently
becomes bifid dorsally, as in the dorsal elements. The me-
dial ramus of the CPOL contacts the TPOL instead of the
postzygapophysis, as in Rocasaurus muniozi (MPCA-Pv 859),
but in Ibirania parva these laminae possibly create a paired
TPOF (Fig. 4.4). The neural spine is very damaged, hamper-
ing major observations and comparisons of structure de-
velopment, such as the POSL and the POSF.
Anterior dorsal vertebrae. Anterior dorsal elements of Ibirania
parva include two neural arch fragments (MPPC 02-013 and
MPPC 00-023; see Fig. 8 in Supplementary Online Informa-
tion) and a partially preserved anteriormost dorsal vertebra
(MPMA 08-0050/01; Fig. 5). The position of these partial
neural arches was established through the preserved lami-
nae and the general shape. MPPC 02-013 and MPPC 00-
023 only preserve the anterior part, lacking most of the
neural spines. MPMA 08-0050/01 lacks the left anteroven-
tral region of the centrum, portions of the neural spine, and
transverse processes. Both were designated as referred
specimens of Ibirania parva, because they exhibit some of
the autapomorphies present in the posterior dorsal material
of the holotype (LPP-PV-0200).
The anterior surface of MPPC 02-013 and MPPC 00-023
preserves a thick PRSL, as seen in Notocolossus
gonzalezparejasi (González Riga et al., 2016). This lamina
extends through the entire neural spine in both elements,
and in MPPC 00-023, it is accompanied by prominent
SPRLs, as in Uberabatitan ribeiroi (Silva Jr et al., 2019).
However, in Ibirania parva the SPRL are closer to the PRSL
than in other titanosaurians (see Fig. 9 in Supplementary
Online Information). Above the SPRL, an incipient crest can
be observed on the PRSL of MPPC 02-013 (Fig. 7 in
Supplementary Online Information). In MPPC 02-013, the
ventral portion of PRSL increases into a broad profile, as in
MPMA 08-0050/01 and in Patagotitan mayorum, differing
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Figure 4. Referred posteriormost cervical vertebra of Ibirania parva gen. et sp. nov. (MPMA 08-0049-02). 1, right lateral view; 2, anterior view;
3, left lateral view; 4, posterior view; 5, dorsal view; 6, ventral view. Anatomical abbreviations: ACDL, anterior centrodiapophyseal lamina; as,
articular surface; CDF, centrodiapophyseal fossa; CPOL, centropostzygapophyseal lamina; CPRL, centroprezygapophyseal lamina; ct, cotyle; dp,
diapophysis; ep, epipophysis; fo, foramen; ict, internal camellate tissue; lat. SPOL, lateral spinopostzygapophyseal lamina; med. SPOL, medial
spinopostzygapophyseal lamina; nc, neural canal; nt, notch; pc, pleurocoel; PCDL, posterior centrodiapophyseal lamina; POCDF, posterior
centrodiapophyseal fossa; PODL, postzygodiapophyseal lamina; poz, postzygapophysis; pp, parapophysis; PRDF, prezygodiapophyseal fossa;
prz, prezygapophysis; TPOL, intrapostzygapophyseal lamina; TPOF, intrapostzygapophyseal fossa. Scale bar equals 10 cm.

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from the tripartite condition of Mendozasaurus neguyelap
(González Riga et al., 2018). Only a small part of the SPDL is
preserved on both neural arches, showing that the neural
spine, although not fully preserved, possesses subparallel
lateral margins that slightly converge on the dorsal end. In
addition, the SPDL shows no signs of split on its preserved
portion, with diapophyses developing slightly laterally
than upward as in Trigonosaurus pricei and Overosaurus
paradasorum (Campos et al., 2005; Coria et al., 2013).
The most complete anterior dorsal (MPMA 08-0050/01)
represents either the first or second dorsal vertebra, given
that its parapophysis stands slightly above the level of the
preserved anterior margin of the pleurocoel (Fig. 5.1). Ex-
cept for a minor part of the right lateral side, the centrum is
strongly displaced to the right side and crushed sagitally,
revealing the “honeycomb-like” internal tissue with large
cells. The zygapophyses and diapophyses are not preserved,
but their probable positions can be assessed through asso-
ciated laminae. The prezygapophyses are bounded by a
sharp and thin TPRL that is well developed anteriorly (Fig.
5.2, 5.5). Ventrally, a thick single CPRL is preserved on the
right side, bordering a shallow CPRF. This condition differs
from that present in Saltasaurus loricatus, in which the CPRL
is divided into two distinct rami (i.e., lat. CPRL and med.
CPRL; see Fig. 9 in Supplementary Online Information). Pos-
terodorsally, the prezygapophyses are linked to the neural
spine by a strongly developed SPRL, which accompanies the
curvature of the neural spine (Fig. 5.2). Together with the
SPRL, the PODL and lateral SPOL delimit a broad and deep
PRSDF (Fig. 5.3), which on the left side is internally divided
by a small accessory lamina (Fig. 5.4) that connects the
lateral SPOL to the possible medial end of the SPDL. This
laminae-fossae pattern could be homologous to the con-
dition seen in the mid-cervical vertebrae of Rapetosaurus
krausei, Uberabatitan ribeiroi, and DGM Series A (MCT 1487-
R), in which the EPRL extends across the SDF and divide
it into two secondary depressions (Curry Rogers, 2009;
Wilson, 2012; Silva Jr et al., 2019). However, this accessory
lamina has an asymmetrical development, and the absence
of other axial elements sharing its presence hampers a
better assessment of how this feature develops along the
dorsal series.
The transverse processes are not preserved, except for
the right parapophysis. A sharp ridge extends posteriorly
to the parapophysis and reaches the ventrolateral margin
of the cotyle (Fig. 5.1), as in the first dorsal vertebra of
Trigonosaurus pricei and MCT 1487-R. However, this could
represent a taphonomical artifact due to the extremely
damaged condition displayed by the preserved centrum and
could be related to the anterodorsal margin of the pleuro-
coel. In lateral view, a very damaged vertical PPDL is pres-
ent, bounding a deep, triangular-shaped PACDF with the
PCDL and posteroventral ridge of the parapophysis. The
PCDL is present as a slender lamina that develops also
posteroventrally, above the posteroventral ridge of the
parapophysis. The PODL are strongly laterally developed,
forming an extensive posterodorsal roof to the POCDF
(Fig. 5.3–5.5). This fossa is trapezoidal in shape, and ex-
tremely deep on its medial face. No evident signs of a SPDL
are observable on its proximal end. Nonetheless, the SPRL
appears to widen distally, and appears bifurcated into a pos-
terior ramus that could correspond to a SPDL (Fig. 5.5).
The neural spine appears to lack only its dorsal surface
(Fig. 5.2, 5.5), displaying lateral margins that gently curve
toward its dorsal end and creating a tapered and low profile
to the neural spine like the one present in Trigonosaurus pricei,
Notocolossus gonzalezparejasi, and other titanosaurians (see
Fig. 9 in Supplementary Online Information). However, the
neural spine in Ibirania parva apparently does not strongly
project posteriorly as in these taxa, resembling more the
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Figure 5. Referred anteriormost (first or second) dorsal vertebra of Ibirania parva gen. et sp. nov. (MPMA 08-0050-01). 1, right lateral view; 2,
anterior view; 3, left lateral view; 4, posterior view; 5, dorsal view. Anatomical abbreviations: accl, accessory lamina; bg, bulge; CPRL, centro-
prezygapophyseal lamina; ct, cotyle; ict, internal camellate tissue; lat. CPOL, lateral centropostzygapophyseal lamina; lat. SPOL, lateral spino-
postzygapophyseal lamina; med. CPOL, medial centropostzygapophyseal lamina; med. SPOL, medial spinopostzygapophyseal lamina; nc, neural
canal; ns, neural spine; PACDF, parapophyseal-centrodiapophyseal fossa; PCDL, posterior centrodiapophyseal lamina; POCDF, postzy-
gapophyseal-centrodiapophyseal fossa; PODL, postzygodiapophyseal lamina; POSF, postspinal fossa; POSL, postspinal lamina; poz, postzy-
gapophysis; pp, parapophysis; PPDL, paradiapophyseal lamina; PRSDF, prezygapophyseal-spinodiapophyseal fossa; PRSL, prespinal lamina;
prz, prezygapophysis; rd, ridge; SPDL, spinodiapophyseal lamina; SPRL, spinoprezygapophyseal lamina; TPOL, intrapostzygapophyseal lamina;
TPRL, intraprezygapophyseal lamina. Scale bar equals 10 cm.

straight condition present in Isisaurus colberti (Jain &
Bandyopadhyay, 1997) and saltasaurines (Zurriaguz &
Powell, 2015). A stout PRSL is present through the entire
extension of the neural spine. This lamina slightly expands
ventrally in a smooth ellipsoid bulge as in Patagotitan
mayorum (see Fig. 9 in Supplementary Online Information).
Likewise, the posterior surface of the neural spine bears a
stout POSL along all its height, also displaying a bulge that
increases ventrally and a broad elliptical POSF with its ven-
tral surface extending close to the cotyle margin due to a
strong development of the TPOL (Fig. 5.4, 5.5).
As with the last cervical and posterior dorsal elements,
the CPOL is dorsally divided into lateral and medial rami in
the anterior dorsal vertebra. The postzygapophyses are not
fully preserved in this element, but the lateral CPOL extends
ventrolaterally below their insertion point. In turn, the me-
dial CPOL extends posterodorsally and merges with the
TPOL. The CPOL split in Ibirania parva differs from that pres-
ent in other titanosaurs, such as Mendozasaurus neguyelap.
In Ibirania parva the bipartite CPOL lacks a fossa between
its medial and lateral rami, which the medial being more
developed than the lateral ramus (Fig. 5.4). By contrast, in
Mendozasaurus neguyelap the split is marked with the de-
velopment of a small triangular fossa which, although it oc-
curs asymmetrically, the lateral branch is more developed
than the medial one. The SPOL is very damaged but appears
to be stout. In dorsal view this lamina also is divided into
two segments, with the lateral ramus being visible anteri-
orly and laterally, whereas the medial one is visible only in
posterior view and approaches the dorsal extremity of the
POSL.
Posterior dorsal vertebrae. Two mid-to-posterior dorsal
elements were recovered, including a referred centrum
(MPPC 02-015; Fig. 10 in Supplementary Online Informa-
tion) and the near-complete holotypic vertebra (LPP-PV-
0200; Fig. 6). As observed in several other titanosaurians,
the mid-to-posterior dorsal centra of Ibirania parva are
higher than wide in cross section, compressed transversely,
strongly opisthocoelous, and anteroposteriorly elongated
(Fig. 6.1, 6.3, 6.6). This morphology differs from some
Brazilian titanosaurs (e.g., Tapuiasaurus macedoi), which dis-
play mid- to posterior dorsal centra that are as wide as
high and anteroposteriorly short (Zaher et al., 2011). The
cotyle in Ibirania parva possesses a sub quadrangular out-
line (Fig. 6.4) differing from the circular shape present in
some saltasaurine titanosaurians (e.g., Saltasaurus loricatus,
Rocasaurus muniozi). However, mid- to posterior dorsal
centra of Ibirania parva lacks the strong dorsoventral com-
pression shared by several Brazilian titanosaurs, such as
Trigonosaurus pricei and Uberabatitan ribeiroi (Campos et al.,
2005; Salgado & Carvalho, 2008). In addition, Ibirania parva
mid- to posterior dorsal centra lack a ventral keel (Fig. 6.6)
as in Barrosasaurus casamiquelai (Salgado & Coria, 2009). As
in other titanosaurians, the mid- to posterior dorsal centra
exhibit the characteristic narrow and deep pneumatopores
with acuminate posterior border (Fig. 6.1, 6.3), which are
enclosed medially by a thin bony septum (Fig. 11 in Supple-
mentary Online Information). The left surface of the pos-
terior dorsal centrum is partially eroded, allowing the
observation of a highly pneumatized internal tissue with a
complex somphospondylous system, which the trabeculae
of the internal cells are formed by typical spongy bone
tissue (Fig. 11 in Supplementary Online Information).
The neural arch pedicel height on LPP-PV-0200, from
the dorsal border of the cotyle until to the ventral limit of
the TPOL, is subequal than to centrum height (Fig. 6.4). The
neural spine is relatively low and strongly inclined relative
to the vertical axis of the vertebra (ca. 45º), in which its
posterodorsal tip surpasses the level of the cotyle edge
(Fig. 6.5). In addition, the lateral surface of the neural spine
features a series of small pneumatic wrinkles (Fig. 11 in
Supplementary Online Information). The distal parts of the
diapophyses and parapophyses are not preserved, and the
left prezygapophysis is missing. The right prezygapophysis
is damaged anteriorly, but it preserves an expanded lami-
nar border on the articular surface, like the condition pres-
ent in dorsal vertebrae attributed to Malawisaurus dixeyi
(Gomani, 2005). However, in Ibirania parva that laminar bor-
der tapers medially (Fig. 6.3) whereas in Malawisaurus dixeyi
it has a rounded outline. Hyposphene-hypantrum articula-
tions are not present in Ibirania parva (Fig. 6.2).
In anterior view, the prezygapophysis is ventrally sup-
ported by a thin and sharply developed CPRL that widens
both ventrally and dorsally. This lamina smoothly merges
ventrally to the prezygapophysis and forms an accentuated
lateral rim for the CPRF (Fig. 6.2, 6.3; see Fig. 11 in Supple-
mentary Online Information). This pattern appears to be
unique to Ibirania parva, because other titanosaurians ex-
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332

hibit restricted CPRF above the neural canal (e.g., Uberabati-
tan ribeiroi, Maxakalisaurus topai, Tapuiasaurus macedoi; Fig.
12 in Supplementary Online Information). The CPRF in these
taxa is developed between a dorsal splitting of CPRL, where
its lateral ramus is expanded laterally, sometimes merging
with the ACPL – absent on the posterior dorsal of Ibirania
parva – and contacting below prezygapophyses. By con-
trast, the medial ramus connects to a ventral ramus of the
TPRL above the neural canal or directly ventrally to the
prezygapophyses, as in the unnamed titanosaurian DGM
775-R and Barrosasaurus casamiquelai. Ibirania parva likewise
differs from the condition shared by Lirainosaurus astibiae,
Trigonosaurus pricei, Overosaurus paradasorum, Muyelensaurus
pecheni, and, in part, Bonitasaura salgadoi, in which the CPRL
and the ventral ramus of TPRL do not fully enclose the CPRF
laterally and medially (see Fig. 12 in Supplementary Online
Information). Ibirania parva CPRL-CPRF morphology also
differs from the condition, present in Opisthocoelicaudia
NAVARRO ET AL.: A NANOID TITANOSAUR FROM BRAZIL
333
Figure 6. Posterior dorsal vertebra of Ibirania parva gen. et sp. nov. holotype (LPP-PV-0200). 1, right lateral view; 2, anterior view; 3, left
lateral view; 4, posterior view; 5, dorsal view; 6, ventral view. Anatomical abbreviations: al, additional lamina; alp, aliform process; ant. SPDL,
anterior spinodiapophyseal lamina; as, articular surface; bg, bulge; cr, crest; CPRF, centroprezygapophyseal fossa; CPRL, centroprezy-
gapophyseal lamina; ct, cotyle; fo, foramina; gr, groove; ict, internal camellate tissue; lat. CPOL, lateral centropostzygapophyseal lamina; lat.
SPOL, lateral spinopostzygapophyseal lamina; nc, neural canal; nt, notch; ns, neural spine; med. CPOL, medial centropostzygapophyseal
lamina; med. SPOL, medial spinopostzygapophyseal lamina; PCDL, posterior centrodiapophyseal lamina; PCPL, posterior centroparapophy-
seal lamina; pn, pneumatopore; POCDF, postzygapophyseal-centrodiapophyseal fossa; PODL, postzygodiapophyseal lamina; POSDF, postzy-
gapophyseal-spinodiapophyseal fossa; POSF, postspinal fossa; POSL, postspinal lamina; pos. SPDL, posterior spinodiapophyseal lamina; poz,
postzygapophysis; pp, parapophysis; PPDL, paradiapophyseal lamina; PRPADF, prezygapophyseal-paradiapophyseal fossa; PRSDF, prezy-
gapophyseal-spinodiapophyseal fossa; PRSF, prespinal fossa; PRSL, prespinal lamina; prz, prezygapophysis; SDF, spinodiapophyseal fossa;
SPRL, spinoprezygapophyseal lamina; TPRL, ventral intraprezygapophyseal lamina; TPOL, intrapostzygapophyseal lamina; ven. TPRL, ventral
ramus of the intraprezygapophyseal lamina. Scale bar equals 10 cm.

skarzynskii, Epachthosaurus sciuttoi, Dreadnoughtus schrani, and
Elaltitan lilloi, which the CPRL and ACPL are merged in a thick
single lamina that forms pedicels in the neural arch, resulting
in a deeper undivided CPRF (Fig. 12 in Supplementary Online
Information). On the other hand, some titanosaurians
from Peirópolis (CPPLIP-0035) and saltasaurines such as
Neuquensaurus australis and Saltasaurus loricatus exhibit a
similar morphology to Ibirania parva, differing by the CPRL
developed that are widened and flat, as well as in the
presence of a ventral ramus of the TPRL and/or additional
internal pneumatopores on CPRF (see Fig. 12 in Supple-
mentary Online Information).
The lateral borders of the neural canal in Ibirania parva
are laminar, but there is no contact with the ventral ramus
of the TPRL. The latter slightly extends vertically above the
neural canal and ends dorsally in a “pendant-shaped” bulge,
which is anteriorly flattened and pierced by a small foramen.
The dorsal ramus of the TPRL extends posteriorly, where it
becomes the border for a single and medially placed elon-
gated sulcus that extends anteroventrally to the PRSL.
Additionally, the dorsal surface of the TPRL converges with
the posterior end of the SPRL, forming accessory laminae
in both sides of the PRSL. These accessory PRSL does not
expand laterally from its ventral portion – as in Uberabatitan
ribeiroi – but extends over half of its length (see Fig. 11 in
Supplementary Online Information). The PRSL is well devel-
oped and robust, almost “rod-shaped”, bearing a rugose
crest at its mid-height (Fig. 6.2, 6.5). This morphology is in-
terpreted here as another autapomorphic condition of Ibira-
nia parva. Like the PRSL, the POSL is thick and is present
along the entire height of the neural spine.
Parapophyses and diapophyses are incomplete, but
their position can be inferred from associated laminae. The
latter project more dorsally than dorsolaterally, as in other
saltasaurines (Zurriaguz & Powell, 2015). As mentioned
above, the ACPL is absent, whereas the PCPL is well-devel-
oped and extends posteriorly close to the dorsal margin of
cotyle, like the anterior dorsal vertebrae (MPMA 08-
0050/01). The PCPL with the PCDL delineates a deeper
PRPADF, as in Bonatitan reigi (Salgado et al., 2015), and is
medially surrounded by a thin and well-developed PPDL.
Ventral to this fossa, the surface is mostly flat and fea-
tureless. The diapophyses are supported by a robust PCDL.
The anterior portion extends anteroventrally but does not
reach the dorsal border of the centrum. The posterior ramus
is highly conspicuous and projects anterodorsally from the
posterior border of the centrum. It is softly curved and then
becomes straighter dorsally, closer to the diapophysis,
with its lateral surfaces almost flat. A shallow depression
is present on the widened end of the PCDL (Fig. 6.1, 6.3),
differing from the condition present in other saltasaurines,
such as Saltasaurus loricatus, Neuquensaurus australis, and
Rocasaurus mu ni ozi, which possess an excavated CDF
(Zurriaguz & Powell, 2015).
The SPDL is bifurcated, as in several lithostrotians (e.g.,
Bonitasaura, Rapetosaurus), exhibiting an anterior and a pos-
terior ramus (Salgado et al., 1997; Salgado & Powell, 2010).
The split of SPDL occurs proximally, differing from some
taxa such as Trigonosaurus pricei, which an incipient split
occurs nearer to the diapophyses than to the neural spine.
In Ibirania parva, both SPDL rami are robust and border a
dorsally opened and deep SDF, unlike other saltasaurines
such as Neuquensaurus australis and Saltasaurus loricatus.
The anterior ramus of the SPDL is closely appressed to the
neural spine, and then extends laterally, converging with the
posterior ramus of the SPDL. In turn, the posterior ramus
projects more posterodorsally than the anterior one, inter-
preted here as an autapomorphic condition (Fig. 6.2). Its me-
dial end is curved ventrally to an incipient aliform process,
without contribution to the latter. The aliform process is re-
duced and damaged, but its base seems oriented perpendi-
cular to the neural spine axis (Fig. 6.1). Laterally the main
SPDL is almost horizontal, bearing a convex dorsal surface.
The postzygapophysis has a wide articular surface. Its
posterior border tapers and slightly curves dorsally, forming
a sharp posterior corner (Fig. 6.1). Ibirania parva possesses
two SPOLs, medially and laterally contacting the postzy-
gapophysis to the neural spine. Paired SPOL are typical of
non-titanosaurian sauropods, such as rebbachisaurids
(Wilson, 1999, 2012), but can also appear in some ti-
tanosaurians (e.g., Lirainosaurus astibiae,Bonitasaura salgadoi).
In Ibirania parva the medial lamina, with the POSL, forms a
restricted POSF shaped as a vertical trough (Fig. 11 in Sup-
plementary Online Information). The lateral lamina bifur-
cates dorsally, into rami directed anterodorsally in an area
marked by pneumatic wrinkles (Fig. 6.1, 6.4). This split is
produced by the development of an enlarged pneumatic
foramen anteriorly and between the lat. SPOL ramus (Fig.
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11 in Supplementary Online Information). The TPOL, al-
though is not fully preserved, appears to exhibit a nearly
“U-shape” and projects posteriorly as far the postzyga-
pophyses.
Ibirania parva displays a thin PODL, which is preserved
only on the left side (Fig. 6.1, 6.3). This lamina is present in
Andesaurus delgadoi, Epachthosaurus sciuttoi, Rapetosaurus
krausei, Overosaurus paradasorum, Neuquensaurus australis,
and Saltasaurus loricatus (Salgado et al., 2005; Salgado &
Powell, 2010; Zurriaguz & Powell, 2015), but absent in
Opisthocoelicaudia skarzynskii, Muyelensaurus pecheni,
Ampelosaurus atacis, Lirainosaurus astibiae, Rocasaurus
muniozi, and Bonatitan reigi.
As in the posteriormost cervical and anteriormost dorsal
vertebrae, the medial CPOL are dorsally bipartite, but in the
mid- to posterior dorsal vertebra the laminae development
is asymmetric (Fig. 6.4). In the left medial CPOL, the lateral
and medial rami are equally developed and separated by a
shallow vertical groove. However, a conspicuous additional
ridge between the two rami marks the right medial CPOL
complex. The medial CPOL are straight, delimiting a single
and deep CPOF. Unfortunately, the fragmentary condition
of this fossa prevents the confirmation of a ventral ramus
of the TPOL, as present in Bonitasaura salgadoi, Rocasaurus
muniozi, and Bonatitan reigi. The lateral CPOL forms a promi-
nent rim through most of its length, but it expands an-
teroventrally and merges with the posterodistal end of the
PCDL, forming a continuous ventral ridge to the POCDF, as in
Malawisaurus dixeyi. With the PODL, the PCDL and the lateral
CPOL delimit a ventrally excavated POCDF. In Ibirania parva
the POCDF is better preserved on the left side of the neural
arch, where it shows an enlarged “V-shaped” foramen an-
teroventral to the PODL (Fig. 6.3), a feature only shared with
Saltasaurus loricatus. The absence of such foramen on the
right side of the neural arch could be explained either by
asymmetric development or by the collapse of the PODL
due to the lateral diagenetic compression. The presence of
several foramina along the cervicodorsal neural arches and
the complex camellate pattern in the centra indicate strong
pneumaticity in Ibirania parva.
Caudal vertebrae. Four caudal vertebrae were associated
with the Ibirania parva: three (LPP-PV 0204–0206) were re-
covered with the rest of the material assigned to the holo-
type and one (MPMA 08-0060/07) was found in adjacent
outcrops. The latter shares with the holotype of Ibirania
parva a short prezygapophysis and a low, posterodorsally
projecting neural spine, differing in that way from other
caudal morphotypes from the same unit (Navarro et al.,
unpublished data).
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Figure 7. Biconvex first caudal centrum of Ibirania parva gen. et sp.
nov. holotype (LPP-PV-0204). 1, right lateral view; 2, left lateral view;
3, dorsal view. Anatomical abbreviations: acd, anterior condyle; ict,
internal camellate tissue; nap, neural arch pedicel; nc, neural canal;
pcd, posterior condyle; pn, pneumatopore; st, striae; tp, transverse
process; vlf, ventrolateral fossa. Scale bar equals 10 cm.

LPP-PV-0204 (Fig. 7) consists of a partially preserved
first caudal centrum (or last sacral according to D’Emic &
Wilson, 2011). This element possesses a biconvex articula-
tion, as in Neuquensaurus australis, Antarctosaurus wichman-
nianus, Alamosaurus sanjuanensis, Pellegrinisaurus powelli,
and Baurutitan britoi. The giant titanosaurian Dreadnoughthus
schrani has been also interpreted as possessing a biconvex
centrum in the first caudal vertebra (Lacovara et al., 2014),
but the presence of wide ventrolateral transverse processes
and a flat anterior portion of the centra suggest that this el-
ement in fact corresponds to a non-biconvex sixth sacral
vertebra. In addition, the preserved sacrum of Dreadnoughtus
schrani was recovered articulated to its caudal series and
displays only five sacral elements (see supplementary
figures 13 and 14 of Lacovara et al., 2014).
The first caudal centrum Ibirania parva shares with
Saltasaurus loricatus a small pneumatopore on the lateral
surface of the centra (Fig. 7.1), indicating a conspicuous
internal pneumatization on anterior caudal vertebrae
(Zurriaguz & Cerda, 2017). Dorsally, the pneumatopore
bears several smooth stripes, which may be associated with
the development of diverticula. The left lateral side is badly
preserved (Fig. 7.2), allowing the view of a somphospondy-
lous internal tissue with small-sized cells. Most of the neu-
ral arch is absent due to recent weathering (Fig. 7.1, 7.3),
preserving solely a damaged ventral end of transverse
processes on the right side and parts of the neural arch
pedicel, where neurocentral joints are not visible in the pe-
riosteum. The preserved part of neural arch pedicel bears a
conspicuous lateral fossa with a rounded shape. Although
damaged, the centrum also displays a marked constriction
at its mid-length (Fig. 7.3).
The holotypic middle neural arch (LPP-PV-0206) only
preserves its dorsal portion, lacking the prezygapophyses
(Fig. 8). In anterior view, a marked PRSF is present bearing an
incipient ventral PRSL. The neural spine is low, transversely
compressed and strongly posterodorsally projected as in
other saltasaurines (Fig. 8.1, 8.3). Posteriorly, the neural
spine displays a broad POSF that is filled by a wide POSL on
the entire preserved dorsoventral extension (Fig. 8.4), as in
Saltasaurus loricatus, Bonatitan reigi (Martinelli & Forasiepi,
2004; Zurriaguz & Cerda, 2017), and MPMA 08-0060/07.
The postzygapophyses are flat, lacking postzygapophyseal
bony processes and laterally developed hyposphenal ridges.
The partial posterior centrum (LPP-PV-0205) is badly
preserved, lacking most of its anterior portion and the whole
neural arch (Fig. 8.5, 8.8). As in MPMA 08-0060-07, the cen-
trum is strongly procoelous and as wide as high, slightly
dorsoventrally compressed (quadrangular in shape). Unlike
some saltasaurines such as some Neuquensaurus speci-
mens, which have an internal pneumatization in the caudal
series restricted to the middle caudal elements, in Ibirania
parva this pattern appears to reach the most posterior ele-
ments. LPP-PV-0205 preserves a somphospondylous in-
ternal tissue similar to that in Saltasaurus loricatus and
Rocasaurus muniozi (Zurriaguz & Cerda, 2017).
The referred mid- to posterior caudal element (MPMA
08-0060/07) is nearly complete (Fig. 9). The centrum has a
quadrangular shape (as wide as high) in anterior view, being
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Figure 8. Partial middle caudal neural arch and posterior caudal cen-
trum of Ibirania parva gen. et sp. nov. holotype (LPP-PV-0206 and
LPP-PV-0205, respectively). 1, 5, right lateral view; 2, 6, anterior
view; 3, 7, left lateral view; 4, 8, posterior view. Anatomical abbre-
viations: as, articular surface; cd, condyle; fo, foramen; ict, internal
camellate tissue; nap, neural arch pedicel; nc, neural canal; ns, neural
spine; POSF, postspinal fossa; poz, postzygapophysis; PRSF,
prespinal fossa; PRSL, prespinal lamina; TPOL, intrapostzygapophy-
seal lamina. Scale bar equals 5 cm.

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Figure 9. Referred middle caudal vertebra of Ibirania parva gen. et sp. nov. (MPMA 08-0060-07). 1, right lateral view; 2, anterior view; 3, left
lateral view; 4, posterior view; 5, dorsal view; 6, ventral view. Anatomical abbreviations: as, articular surface; cd, condyle; ct, cotyle; ict, inter-
nal camellate tissue; nc, neural canal; ns, neural spine; poz, postzygapophysis; PRSF, prespinal fossa; prz, prezygapophysis; rd, ridge; TPRL,
intraprezygapophyseal lamina. Scale bar equals 5 cm.

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anteroposteriorly short, strongly procoelous, and lacking
marked lateral depressions. Ibirania parva bears an anteri-
orly deflected cotyle margin in lateral view (Fig. 9.1, 9.3), as
present in Gondwanatitan faustoi, Uberabatitan ribeiroi, the
holotype of Neuquensaurus australis (MLP-Ly 4 - 5), and
Rocasaurus muniozi (MPCA-Pv 58). As in Baurutitan britoi, the
centrum preserves incipient tuberosities posterolaterally
(Fig. 9.3–9.5) that are reminiscent of the transverse
processes where the M. ilioischiocaudalis inserts (Díez-
Díaz et al., 2020). On the lateral and ventral surface of the
centrum, it is possible to visualize an elaborate som-
phospondylous internal tissue. A shallow and transversely
wide ventral hollow is present (Fig. 9.6) as in most
saltasaurids (Sanz et al., 1999; Salgado & Azpilicueta, 2000),
but lacking a median bony septum as seen in Rocasaurus
muniozi and Saltasaurus loricatus (Zurriaguz et al., 2017).
Ibirania parva mid- to posterior caudal vertebra also lacks
prominent ventrolateral ridges. The neural arch is low and
with short prezygapophyses, as in Bonatitan reigi (Martinelli
& Forasiepi, 2004). However, the prezygapophyses are ro-
bust, slightly curved medially (Fig. 9.1, 9.5), with the articu-
lar surfaces strongly obliquely oriented. The SPRL and TPRL
are well marked and thick, mainly the latter, bordering a
deep PRSF. The TPRL develops anteriorly, projecting beyond
the cotyle margin (Fig. 9.6). As in LPP-PV-0206, the PRSL
of MPMA 08-0060/07 is almost absent, and the neural
spine is low and strongly posterodorsally projected, bearing
a ventrally broad POSL filling the posterior surface. The
postzygapophyses are flat, with an outline that tapers pos-
terodorsally, lacking postzygapophyseal bony processes
and laterally developed hyposphenal ridges laterally devel-
oped present in rinconsaurians and Epachthosaurus sciuttoi
(Martínez et al., 2004; Calvo et al., 2007).
Appendicular skeleton
Radius. LPP-PV-0203 (Fig. 10.1–10.5) is a fragmentary di-
aphyseal bone lacking most of its anteromedial surface and
proximal half (Fig. 10.2, 10.4). This element is identified as
the distal half of a right radius due to its ellipsoid shape at
mid-section. Only the anterolateral and posterolateral sur-
faces of the diaphyseal region are preserved, bearing a
slightly convex profile. As in Yamanasaurus lojaensis, it is not
possible to recognize interosseous ridges over the diaph-
ysis, as expected for the posterior surface (Apesteguía et al.,
2020). In turn, the posteromedial margin displays a thick
ridge, continuous with the rest of the bone margin, which
gradually expands transversely towards its distal end (Fig.
10.1). Given its fragmentary condition, we cannot assess if
it had an obliquely oriented ventral margin or expanded
ends, as in other saltasaurines (Powell, 1992).
Ulna. The holotype of Ibirania parva also preserves a
fragmentary right ulna (LPP-PV-0202; Fig. 10.6–10.10)
lacking its extremities. Its identification was based on the
comparison with appendicular materials from other ti-
tanosaurians and the characteristic “D-shaped” diaphyseal
cross section, for which some histological samples were
prepared (see below). The proximal end exhibits a very frag-
mentary condition, not preserving an olecranon, or the an-
teromedial and anterolateral processes; the distal end is
only slightly abraded.
The proximal portion appears to be wide, consistent with
the typical tri-radiate shape. The radial fossa consists of a
flattened area, lacking interosseous ridges. In the posterior
view, in turn, the bone exhibits a convex profile, and the dis-
tal end preserves two parallel ridges directed proximodis-
tally (Fig. 10.9), possibly representing muscular scars for the
M. flexor carpi ulnaris (Borsuk-Białynicka, 1977). Addition-
ally, there is an ellipsoid pit located close to the distal end,
visible in the posterolateral view, which probably served as
the insertion point of the radial ligament. This latter condi-
tion appears autapomorphic to Ibirania parva, although the
hypothesis that such trait may correspond to pathology
cannot be dismissed.
The diaphyseal shape has straight lateral and medial
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Figure 10. Forelimb bones of Ibirania parva gen. et sp. nov. holotype. Partial right radius (LPP-PV-0203) in 1, lateral view; 2, anterolateral view;
3, anteromedial view; 4, medial view; 5, posteromedial view; partial right ulna (LPP-PV-0202) in 6, lateral view; 7, posterolateral view; 8, pos-
teromedial view; 9, medial view; 10, anteromedial view; distal half of metacarpal III (LPP-PV-0201) in 11, lateral view; 12, anterolateral view;
13, medial view; 14, posteromedial view; 15, midshaft in cross section view; 16, distal view. Anatomical abbreviations: alm, anterolateral mar-
gin; amm, anteromedial margin; dex, distal end expansion; gr, groove; ior, interosseous ridge; mc, metacarpal; ms, muscular scar; pmm, pos-
teromedial margin; pt, pit; rd, ridge; sc, sulcus. Scale bars equals 5 cm.

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margins, with the beginning of the expansion marked by the
slight development of the lateral and medial processes.
This could mean, although not preserved, that the proximal
end was not as expanded as in other titanosaurians (e.g.,
Diamantinasaurus matildae, Elaltitan lilloi, Epachthosaurus
sciuttoi, Opisthocoelicaudia skarzynskii). The profile present
in the ulna of Ibirania parva differs from the slender nature
of some titanosaurians, such as Rapetosaurus krausei (Curry
Rogers, 2009) and Narambuenatitan palomoi (Filippi et al.,
2011), resembling the robust condition of Neuquensaurus
australis and other saltasaurines (Otero, 2010; Tab. 2).
Metacarpal. The distal half of a right metacarpal III (LPP-
PV-0201; Fig. 10.11–10.16) was identified due to the
triangular-shaped cross section at the mid-shaft (Fig.
10.13) and through comparisons with other taxa that
preserve more complete manual material, including
Argyrosaurus superbus, Elaltitan lilloi, Neuquensaurus australis,
Diamantinasaurus matildae, Opisthocoelicaudia skarzynskii,
Mansourasaurus shahinae, and Angolatitan adamastor
(Huene, 1929; Borsuk-Białynicka, 1977; Otero, 2010;
Mateus et al., 2011; Mannion & Otero, 2012; Poropat et al.,
2015; Sallam et al., 2018). It has a pronounced “V-shaped”
depression with marked ridges on the posterolateral facet
of the mid-shaft and converges distally. This depression
extends mediodistally and laterodistally, accompanying an
interosseous ridge (Fig. 10.12). These ridges could represent
scars of the ligaments that kept digits II and IV tightly
bound. The distal end is rectangular in shape (Fig. 10.16) and
lacks the “U-shaped” groove or articular condyles on the
anterior surface, indicating that the manus of Ibirania parva
probably lacked phalanges.
Fibula. Some diaphyseal fragments of a fibula (LPP-PV-
0043), assigned to a referred individual, were recovered near
the holotype stratum. The bone exhibits a slight “D-shaped”
profile in cross section and bears an incipient lateral
trochanter, which is partially preserved. Aureliano et al.
(2021a) described the histological profile of this element and
the pathological alterations caused by acute osteomyelitis
and parasitic infections as well.
The left fibula of Ibirania parva (MPMA 09-0001/99; Fig.
11.1–11.5) is a slender bone only missing parts of its proxi-
mal and distal ends. Nonetheless, the proximal end is seem-
ingly more anteroposteriorly expanded than the distal one
(Fig. 11.1, 11.4). The anterolateral margin in the proximal
end is gently convex, and a possible tibial scar can be pres-
ent (Fig. 11.2). The midshaft on lateral view differs from the
straighter condition of Laplatasaurus araukanicus, Uberabati-
tan ribeiroi, and Mendozasaurus neguyelap (see Fig. 13 in Sup-
plementary Online Information). The lateral trochanter is
slightly developed, present as a smooth tuberosity, as in the
pathological specimen LPP-PV-0043. In addition, the lat-
eral trochanter is in line with the proximodistal axis of the
diaphysis, possibly corresponding to an autapomorphy of
Ibirania parva.
The lateral trochanter is located above the mid-length
of the bone (Fig. 11.3) as in Dreadnoughtus schrani and
Neuquensaurus australis and differing from Rapetosaurus
krausei, in which the lateral trochanter is positioned at the
mid-height of the fibula. In Ibirania parva, the trochanter is
oriented from the anteroproximal to posterodistal faces, as
in several titanosaurians (González Riga et al., 2019), with a
longitudinal and shallow trochanteric fossa dividing it into
two segments. However, the lateral trochanter is less
prominent than in these taxa. In medial view, a wide and
shallow tibial fossa is present proximally. The fibula exhibits
a slight sigmoid profile, due to the presence of a concave
anteromedial margin close to the distal end. Nevertheless,
this outline is less pronounced than the sigmoid profile
exhibited in Epachthosaurus sciuttoi and much more gracile
than the observed in Dreadnoughtus schrani. The preserved
portion of the distal end expands mediolaterally (Fig. 11.5),
giving a smooth excavated fossa that projects towards its
mid-length.
Metatarsal. A probable metatarsal I (LPP-PV-0207; Fig.
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Figure 11. Hind limb bones of Ibirania parva gen. et sp. nov.: referred left fibula (MPMA 09-0001/99) in 1, lateral view; 2, posterior view; 3, pos-
teromedial view; 4, medial view; 5, anteromedial view; holotypic left metatarsal I (LPP-PV-0207) in 6, proximal view; 7, dorsal view; 8, lateral
view; 9, ventral view; 10, medial view; 11, distal views. Anatomical abbreviations: af, anterior fossa; apm, anteroproximal margin; dlm, dorso-
lateral margin; dmm, dorsomedial margin; icg, intercondylar groove; ior, interosseous ridge; lcd, lateral condyle; ls, lateral sulcus; lt, lateral
trochanter; mcd, medial condyle; st, striae; tbf, tibial fossa; tf, trochanteric fossa; vlm, ventrolateral margin; vmm, ventromedial margin. Scale
bars equals 5 cm.

11.6–11.11) is preserved, based in comparison with more
complete pedes (e.g., Mendozasaurus neguyelap, Notocolossus
gonzalezparejasi). This bone is proximodistally elongated
when compared to other titanosaurians like
Opisthocoelicaudia skarzynskii and the Naashoibito pes
referred to Alamosaurus sanjuanensis (D’Emic et al., 2011).
Preserved portions of the proximal and distal ends indicate
they were transversely expanded. The proximal articular
surface slopes ventromedially as in Dreadnoughtus schrani,
Rapetosaurus krausei, and Notocolossus gonzalezparejasi. The
metatarsal shows a slightly concave lateral border with a
subtle lateral ridge. In medial view (Fig. 11.6, 11.7), a
delicate medial ridge appears at mid-length and shows a
poorly pronounced sigmoidal lateral edge. In posterior view
(Fig. 11.9), a minor but accentuated intercondylar groove
appears delimiting transversely the distal articular surface.
The dorsal surface of the distal end is slightly twisted
medially but, in dorsal view, the lateral margins exhibit a
strong lateral deflection, and the articular surface broadly
convex mediolaterally (Fig. 11.6, 11.11).
OSTEOHISTOLOGY
Skeletochronology of Ibirania parva
The holotypic ulna shows no macroscopic damage on its
surface, but thin sections reveal truncated osteons all over
the external bone perimeter (Fig. 12.1). Truncation was
caused by pre-burial and/or post-exhumation transport.
The presence of sandstone grains infilling cavities (mostly
between trabeculae) supports a pre-burial transportation
hypothesis (Fig. 12.2). The abundance of oxide minerals lat-
erally on the surface and infilling vacant spaces in the pe-
riosteum indicates post-exhumation weathering. Despite all
these destructive taphonomic features, the microstructure
is well-preserved, and histology could be assessed (Fig.
12.1–12.6).
The extent and type of vascularization is consistent
across thin sections. The entire cortex has been secondarily
remodeled into dense Haversian bone (Type G to Type H
bone tissue sensu Klein & Sander, 2008; Sander et al., 2011;
also see Fig. 14 in Supplementary Online Information),
lacking an interstitial laminar primary bone (Modified
Laminar Bone sensu Klein et al., 2012) as present in some
Magyarosaurus specimens, Ampelosaurus atacis, and
Rapetosaurus krausei (Stein et al., 2010; Curry Rogers et al.,
2016). Two (possibly three) generations of secondary
osteons overlap one another (Fig. 12.2). These latter are
longitudinally arranged and vary remarkably in size (ranging
from 89–254 µm) and shape. Each secondary osteon
contains up to five layers of centripetally deposited lamellar
bone. Abundant and large resorption cavities throughout the
mid-cortex is indicative of intense bone remodeling at the
time of death. Lines of Arrested Growth (LAGs) have not
been identified in Ibirania parva thin sections, differing from
Neuquensaurus australis (Cerda & Salgado, 2011). This
condition is not uncommon in derived titanosaurians (e.g.,
Woodward & Lehman, 2009; Company, 2011; Klein et al.,
2012; Ghilardi et al., 2016), being more related to the life
history of an individual rather than a developmental pattern
(Curry Rogers & Kulik, 2018; González et al., 2020).
However, there is no evidence of an External Fundamental
System (or Outer Circumferential Layer), indicative of
growth cessation. By contrast, although most of the
outermost cortex of Ibirania parva consists of a dense
Haversian bone, the secondary osteons are horizontally
organized, in non-uniform subparallel patterns (see Fig. 14
in Supplementary Online Information).
Nonetheless, the secondary osteons located in the mid-
dle cortex are chaotically arranged and obliteration in-
creases towards the medullary cavity. The medullary cavity
of the ulna is reduced and filled with cancellous bone (Fig.
12.5), given the cortex displays an ‘average thickness’
(CT/CaM = 0.058; sensu Mitchell & Sander, 2014). Applying
the three-front model of Mitchell and Sander (2014) to the
anterior area of the bone, a “senescent” status was
achieved with this specimen, with both Apposition Front
and the Resorption Front exhibiting slow rates (Fig. 12.6).
PHYLOGENETIC ANALYSIS
Phylogenetic relationships of Ibirania parva
Our phylogenetic analysis resulted in 258 MLTs of 1840
steps (CI = 0.309 / RI = 0.692), showing a well-resolved
topology with the best score being hit 100 times. TBR branch
swapping of these 258 trees found additional optimal trees,
yielding a total of 1080 MPTs. A strict consensus of these is
shown in Figure 13. The complete topology recovered, as
well as Bremer, bootstrap, and jackknife support values for
the consensus tree are given as Supplementary Online
Information. A list of unambiguous synapomorphies
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supporting the nodes of the strict consensus of Figure 13 is
also provided as Supplementary Online Information.
Branch support values for most macronarian nodes re-
ceived low to moderate support values (Table 3). Except
Lithostrotia (2), other more inclusive taxa of the ingroup
(e.g., Titanosauria, Eutitanosauria) exhibit only a low Bremer
support (1). One of the few clades with higher support
values in our analysis corresponds to the Saltasaurinae, in
which Ibirania parva was retrieved, with a Bremer value of 3
and bootstrap and jackknife of 70 and 85, respectively.
Saltasauridae (sensu Sereno, 1998), on the other hand, was
recovered as monophyletic, but received a Bremer of 2 and
was not statistically supported by bootstrap and jackknife
values. Ibirania parva was recovered as the sister taxon of a
new clade within Saltasaurinae, which includes the Argen-
tinian taxa Bonatitan reigi and Rocasaurus muniozi, although
they also clustered with low support values (Bremer of 2
and jackknife of 54). Nonetheless, our analysis corroborates
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Figure 12. Osteohistology of Ibirania parva gen. et sp. nov. holotypic ulna (LPP-PV-0202). 1, Chaotically arranged secondary bone tissue (white
arrows) in anterolateral cortical surface. There are up to five centripetally deposited Haversian layers around osteons. Note that a portion of
the outer cortex was obliterated post diagenesis (blue arrow); 2, Sandstone grains (yellow arrows) infilling medullary spongiosa anterolat-
erally; 3, Haversian osteons in mid-cortex medially. There are at least two generations of secondary osteons overlapping each other. Red arrow
points to potential Sharpey’s fibers; 4, Profile at the medial portion of the shaft. Marked bone deposition fronts according to Mitchell and Sander
(2014); 5, Mid cross section of the ulna with the location of 1–4samples; 6, Three-front model indicating a “senescent” ontogenetic status ac-
cording to Mitchell and Sander (2014). Abbreviations: AF, Apposition Front; HSF, Harversian Front; RF, Resorption Front. Images were taken
under polarized light with crossed nicols in 1–3and parallel nicols in 4. Scale bar in 1, 2equals 500 µm; 3equals 200 µm; 4equals 400 µm;
and 5equals 1 cm.

that Ibirania parva was a saltasaurine titanosaurian, and the
first unequivocally known from Brazil – although some au-
thors have also considered other taxa as putative members
of this group in the past (e.g., Maxakalisaurus topai; Kellner et
al., 2006).
Saltasauridae, recovered here for the first time with
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Figure 13. Temporally calibrated strict consensus tree depicting the phylogenetic affinities of Ibirania parva gen. et sp. nov. within Titanosauria
and the occurrence of nanoid taxa in the group. Colored thick bars represent temporal range of terminal taxa (see Supplementary Online In-
formation) and their spatial distribution according to the key provided in the figure. Age abbreviations: Aal, Aalenian; Alb, Albian; Apt, Aptian;
Bar, Barremian; Ber, Berriasian; Bj, Bajocian; Bt, Bathonian; Cam, Campanian; Cen, Cenomanian; Cl, Callovian; Con, Coniacian; Hau, Hauterivian;
Kim, Kimmeridgian; Maa, Maastrichtian; Oxf, Oxfordian; St, Santonian; Tit, Tithonian; Tur, Turonian; Val, Valanginian.

Baurutitan britoi and Bonatitan reigi, is supported by six
unambiguous synapomorphies: middle to posterior dorsal
centra with slightly concave ventral surfaces, sometimes
with one or two crests (Char. 178: 1→2); neural canal of
middle and posterior dorsal vertebrae enclosed in a deep
fossa in anterior view (Char. 183: 0→1); middle and
posterior dorsal centra with a ventral keel (Char. 186: 0→1);
posterior dorsal neural arches with expanded PCDL ventral
end (Char. 209: 1→0); and opisthocoelous anterior caudal
centra (except for the first) (Char. 231: 3→5, Char. 430:
2→0). Some of these synapomorphies, especially the two
latter, indicate that the morphology displayed by
Opisthocoelicaudia skarzynskii is the plesiomorphic condition
for saltasaurids, being consistent with the acquisition of a
seventh vertebra (representing the biconvex second sacro-
caudal element) observed in the sacrum of saltasaurines.
Saltasaurinae was recovered encompassing a clade
formed by Baurutitan britoi and Alamosaurus sanjuanensis
(two synapomorphies), and a more inclusive clade formed
by Ibirania parva, Bonatitan reigi, and Rocasaurus muniozi, plus
Saltasaurini (three synapomorphies). Synapomorphies
uniting Ibirania parva with the clade formed by Bonatitan reigi
and Rocasaurus muniozi include the presence of a small
notch in the dorsal margin of the posterior cervical cotyle
(Char. 133: 0→1), middle and posterior cervical vertebrae
with the CPOL dorsally divided, with the medial part con-
tacting the TPOL (Char. 144:0→1), and the anterior face of
middle caudal centra strongly inclined anteriorly (Char. 255:
0→1). The clade composed by Bonatitan reigi and Rocasaurus
muniozi is supported by only one unambiguous synapomor-
phy: middle caudal centra quadrangular-shaped, flattened
ventrally and laterally (Char. 250: 1→2).
In addition, we recovered a monophyletic Saltasaurini,
with Neuquensaurus australis as sister group of the clade
formed by the unnamed saltasaurine from Angostura
Colorada Formation (MACN PV RN-233) and Saltasaurus
loricatus. This clade is supported by five unambiguous
synapomorphies, all related to the femoral and caudal mus-
culature: neural spines of the posterior caudal vertebrae
strongly displaced posteriorly (Char. 258: 0→1); the ratio of
centrum length to centrum height in the middle caudal ver-
tebra is 2 or higher (Char. 259: 0→1); presence of a concave
kink on the ventral margin of the ilium preacetabular
processes (Char. 330: 0→1); a longitudinal ridge on the an-
terior face of the femur (Char. 349: 0→1); anterior crest in
the proximal end of fibula absent or poorly developed (Char.
370: 1→0).
Titanosauria was recovered with the following
unambiguous synapomorphies: dorsal vertebrae with
smooth and narrow single PRSL (Char. 165: 1→2); and
middle to posterior dorsal centra with ventral surface
convex transversely (Char. 177: 1→0). Lithostrotia was
recovered outside of Eutitanosauria (as in Hechenleitner et
al., 2020) and supported by two synapomorphies: strongly
procoelous anterior caudal centra (excluding the first ones)
(Char. 231: 2→3); and the absence of ventrolateral ridges
on anterior and mid caudal centra (Char. 234: 1→0). Finally,
Eutitanosauria is characterized by the change of
platycoelous to slightly procoelous condition in the caudal
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TABLE 3. Node support values of the main macronarian clades.
Nodes Br. Bt. Jk.
Macronaria 3 66 83
Somphospondyli 2 - -
Titanosauriformes 2 - -
Brachiosauridae 2 - -
Titanosauria 1 - -
Lithostrotia 2 - -
Eutitanosauria 1 - -
Colossosauria 1 - -
Lognkosauria 1 - -
Rinconsauria 1 - -
Aeolosaurini 1 60 63
Saltasauroidea 1 - -
Diamantinasauria 1 - -
Lirainosaurinae 1 - -
Saltasauridae 2 - -
Opisthocoelicaudiinae 3 74 78
Saltasaurinae 2 52 69
Saltasaurini 3 70 85
A dash (-) denotes when a node support is not recovered. Abbrevia-
tions: Br., Bremer (Decay Index); Bt., Bootstrap; Jk., Jackkinife.

centra (Char. 231: 1→2); and chevrons with a deep haemal
canal, approximately 50% of the chevron length (Char. 270:
0→1).
In our analysis, we also recovered the recently
established clades Lirainosaurinae (Díez-Díaz et al.,
2018), Colossosauria (González Riga et al., 2019), and
Diamantinasauria (Poropat et al., 2021). Additionally, some
other results are consistent with previous analyses, such
as Mansourasaurus as the sister group of Lirainosaurinae
(Sallam et al., 2018) and aeolosaurines more closely related
to Rinconsauria than saltasaurines (Calvo et al., 2007).
However, there are conspicuous differences in the given
topology when compared to previous iterations of this
matrix (i.e., Filippi et al., 2019; Carballido et al., 2020;
Hechenleitner et al., 2020), possibly reflecting the significant
increase in taxon sampling. For example, some taxa such as
Bonitasaura salgadoi is positioned as more closely related to
the giant eutitanosaurians from the Early and early Late
Cretaceous than to other “advanced titanosaurians”–here
represented by colossosaurians and saltasauroids–, and
Diamantinasauria was recovered in a more derived position,
nested into Saltasauroidea, rather in a basal position in
Lithostrotia.
Colossosauria monophyly is recovered through two
unambiguous synapomorphies, but with the differences
as follow: Austroposeidon magnificus is a member of
Lognkosauria and sister taxon of Mendozasaurus
neguyelap, supported by seven synapomorphies, as well as
the cervical series referred to Alamosaurus sanjuanensis
(BIBE 45854), supported by three synapomorphies;
Patagotitan mayorum and Argentinosaurus huinculensis form
a clade outside Lognkosauria, as well as Puertasaurus reuili
and Notocolossus gonzalezparejasi (supported by five
synapomorphies). In addition, the latter clade composes the
sister group of Rinconsauria (supported by three
synapomorphies); Trigonosaurus pricei is the sister taxon of
Overosaurus paradasorum, forming monophyletic group
outside Aeolosaurini (two synapomorphies), as well as
Uberabatitan ribeiroi and Brasilotitan nemophagus (three
synapomorphies), and the group formed by Maxakalisaurus
topai plus Adamantisaurus mezzalirai and Arrudatitan
maximus (three synapomorphies).
The calibrated topology indicates that Rinconsauria
represents an endemic group of South American
colossosaurians whose adaptative radiation occurred after
the Cenomanian–Turonian faunal turnover event. By
contrast, saltasaurids were retrieved in close relation with
globally distributed taxa, forming the clade Saltasauroidea, in
which some minor apical groups such as Saltasaurinae,
Opisthocoelicaudiinae, and Lirainosaurinae, become endemic
due to the isolation of landmasses during the Campanian–
Maastrichtian interval. The clade formed by these groups is
supported by seven synapomorphies: prezygapophyses of
middle cervical vertebrae do not extend beyond the anterior
margin of the centrum (Char. 147: 1→0); SPRL not
contacting the lateral margins of the neural spine of cervical
vertebrae (Char. 151: 0→1); anterior and middle dorsal
neural spines, lacking a SPRL (reversed in Ibirania parva)
(Char. 162: 1→0); middle and posterior dorsal with the
anterior face entirely surrounded by the neural arch (Char.
183: 1→0); anterior and middle caudal vertebrae bearing
ventrolateral ridges and ventral longitudinal hollows (Char.
234: 0→1, Char. 251: 0→1); and humeral distal condyles
exposed on the anterior portion of the shaft (Char. 305:
0→1).
DISCUSSION
Ibirania parva – a nanoid taxon or an immature?
Although Titanosauria includes giant species, Brazilian
titanosaur taxa such as Gondwanatitan faustoi,Trigonosaurus
pricei,Brasilotitan nemophagus, and now Ibirania parva, are
smaller-bodied than their Gondwanan or South American
relatives. Below, we review osteological and histological
data supporting their ontogenetic age estimate. We further
discuss phylogenetic implications and factors that may have
influenced the reduction of body size in Ibirania parva.
Osteological evidence. The degree of neurocentral suture
closure in vertebrae has been widely used as a relative pa-
rameter of archosaurian somatic maturity (see Griffin et al.,
2021). Nonetheless, the closure of the neurocentral suture
as the main parameter of somatic maturity is a labile proxy,
given different patterns in the way of the neurocentral su-
ture is fused have been documented both fossil and extant
archosaurians (e.g., posterior towards anterior elements, an-
terior towards posterior elements; Brochu, 1996; Woodruff
et al., 2017). Thus, its usage in low sample sets (i.e., only two
or fewer axial regions are preserved) should be taken with
caution if it is not complemented by internal anatomy data,
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346

such as CT scan imagery or histological thin sections (Irmis,
2007). Fortunately, cervical, dorsal, and caudal material is
known for Ibirania parva, allowing safely inference of its
somatic maturity.
Although some of such modules of the axial skeleton of
Ibirania parva exhibit fragmentary conditions, most of the
elements have been preserved with the centra fused to
their neural arches. Externally, neurocentral sutures are not
visible in the vertebrae of Ibirania parva (see Figs. 4–7), in-
dicating they are fully fused. CT scan slices also support this
inference (see Fig. 15 in the Supplementary Online Infor-
mation), in which the internal camellate trabeculae appear
continuous. Axial materials of Ibirania parva also display
additional external and internal traits indicative of mature
individuals, such as a high degree of internal pneumaticity
development (Aureliano et al., 2021b) and neural arches
with well-developed laminae and fossae.
These patterns differ from other small-sized and imma-
ture individuals, such as the referred to Rocasaurus muniozi,
Bonatitan reigi, and Bonitasaura salgadoi (Salgado &
Azpilicueta, 2000; Gallina & Apesteguía, 2015; Salgado et
al., 2015), in which many of the preserved dorsal and caudal
neural arches and centra are detached at the neurocentral
suture, sometimes exhibiting a rudimentary development
or slightly marked neural arch laminae.
Histological evidence. Titanosaurians are widely known in
literature due to display a more secondarily remodeled cor-
tical bone tissue compared to other neosauropods (Stein et
al., 2010; Company, 2011; Klein et al., 2012; Cerda et al.,
2017), and the thin sections of Ibirania parva exhibit this pat-
tern. Padian et al. (2016) demonstrated that the cortex of
epipodial bones (i.e., radii, ulnae, tibiae, and fibulae) are more
secondarily remodeled within the same individual than
propodial bones, such as the humerus or the femur. This
pattern could be explained due to higher stress loading ex-
erted in epipodial, mesopodial, and metapodial bones than
in the propodial ones. A similar tissue pattern was also ob-
served both in the ulna and humerus of the Iberian nanoid
titanosaurian Lirainosaurus astibiae (Company, 2011). There-
fore, the proximal limb bones of Ibirania parva could also
have this tissue adaptation.
As in Magyarosaurus (Mitchell & Sander, 2014), the
strong remodeling in the cortex of Ibirania parva was caused
by the slowdown of the Resorption Front, whereas the
Harversian Front is constant across several taxa (Klein et al.,
2012; Mitchell & Sander, 2014). By reducing the speed of
the Resorption Front, Ibirania parva adapted their long bones
with a thick cortex and small medullary volume allowing
this taxon to support an axial loading regime similarly to
Magyarosaurus and Lirainosaurus astibiae. This pattern can-
not be observed in the nanoid macronarian Europasaurus
holgeri or in Rapetosaurus krausei, in which a predominantly
fibrolamellar bone tissue is present in the cortex (Sander et
al., 2006; Curry Rogers et al., 2016).
Other titanosaurians such as Ampelosaurus atacis and
Alamosaurus sanjuanensis also exhibit a greater amount of
Haversian bone when compared to other neosauropods,
such as Apatosaurus (Company, 2011; Klein et al., 2012;
Mitchell & Sander, 2014). However, the extreme abun-
dance of this type of tissue observed in Ibirania parva re-
sembles the condition found in Lirainosaurus astibiae and
Magyarosaurus, rather than any other sampled titanosaurian
in literature, including the small-bodied Patagonian
saltasaurine Neuquensaurus australis, which displays several
LAGs (Cerda & Salgado, 2011). Thus, an effect of analogous
environmental conditions, for example, shared by Ibirania
parva and the insular nanoid titanosaurians from Europe
could convergently culminate in similar decreased apposi-
tion growth in these taxa.
The extreme remodeling activity obliterates completely
the primary bone tissue in the samples of the Ibirania parva
ulna, suggesting that this individual had long ceased appo-
sitional growth at its moment of death, exhibiting a late HOS
(at least HOS 13 from Klein & Sander, 2008). Ibirania parva
exhibit HOS 14, based on the presence of up to five gener-
ations of secondary osteons (Stein et al., 2010; see Fig. 11.1,
11.2, 11.4 in Supplementary Online Information). Further-
more, applying to the anterior area of the bone the three-
front model of Mitchell and Sander (2014), a “senescent”
status is reinforced for this taxon (Fig. 12).
The small body size of Ibirania parva and its implica-
tions
Although body size increase seemingly to be a general
trend in Sauropodomorpha throughout the Mesozoic Era
(phyletic gigantism sensu Gould & Macfadden, 2004; Sander
& Clauss, 2008), episodes of nanism have evolved multiple
times and in different sauropod lineages during the Jurassic
NAVARRO ET AL.: A NANOID TITANOSAUR FROM BRAZIL
347

and Cretaceous (e.g., Stein et al., 2010; Carballido & Sander,
2014). Different evolutionary processes could be associated
with these events (see de Souza & Santucci, 2014; Van der
Geer et al., 2016), including biotic or abiotic pressures, or
even a combination of both. These include “island miniatur-
ization” (e.g., Benton et al., 2010; Weishampel et al., 2010;
Csiki-Sava et al., 2015) as well as niche segregation and
adaptability to a specific feeding strategy (see Whitlock,
2011; Button et al., 2014, 2016; Otero et al., 2021).
In South America, saltasaurines display a conspicuous
reduction in their body sizes, which has been explained as
either a response to geographical restriction to a vast
north-south coastal corridor of the Andean region in the
latest Cretaceous (Apesteguía, 2002; Leanza et al., 2004;
Apesteguía et al., 2020) or to occupation of new and re-
stricted environments formerly occupied by diplodocoid
sauropods (Powell, 2003; Cerda et al., 2012).
Our cladistic analysis recovered Ibirania parva within
Saltasauridae (Fig. 13), in the less inclusive clade
Saltasaurinae and as the sister taxon of a group composed
of the small-bodied Rocasaurus muniozi and Bonatitan
reigi. Thus, the small size exhibited by Ibirania parva would
have been inherited from a common ancestor shared by
Rocasaurus and Bonatitan. Phyletic and autapomorphic
nanism have already been proposed in other titanosau-
rians (e.g., Magyarosaurus dacus, Lirainosaurus astibiae,
Atsinganosaurus velauciensis) from the ancient Ibero-
Armorican Island and the Haţeg Archipelago biota, from the
Campanian–Maastrichtian strata of Europe (Stein et al.,
2010; Klein et al., 2012; Díez-Díaz et al., 2013b; Díez-Díaz
et al., 2018). Except for Magyarosaurus, a possible auta-
pomorphic nanoid, these taxa comprise an endemic clade of
European titanosaurians (Lirainosaurinae) that includes
phyletic nanoid forms, and their phylogenetic relationships
indicate that they are related to the South American
saltasaurids, composing a more inclusive group identified
here as Saltasauroidea.
By contrast, Ibirania parva was recovered in a slightly
older (Santonian–Campanian) continental geological unit,
the intracratonic Bauru Basin, differing from other South
American or European saltasauroid occurrences, which are
found in deposits with marine influence. For this reason, a
nanism occurrence driven by insularity pressures (sensu
stricto) can be excluded in this taxon. If the other
saltasaurines from South America represent true island-
nanoid taxa, the occurrence of Ibirania parva could indicates
a putative phyletic nanism trend, which could be intensified
in other saltasauroids due to insularity pressures.
The inferred paleoenvironmental conditions in the São
José do Rio Preto Formation may have created selective
pressures analogous to those occurring in some typical in-
sular habitats (i.e., differential resource supply and effects
of area size; Van der Geer et al., 2016). The small size ac-
quired by some vertebrate forms in these habitats, such as
the new taxon presented here, could have been a way to
compensate for the implied constraints during prolonged
episodes of aridity.
CONCLUSIONS
Specimens of small-sized titanosaurian morphotype
of the Upper Cretaceous São José do Rio Preto Formation
display a set of autapomorphies–and a unique combination
of characters as well–that differentiate it from other ti-
tanosaurians, supporting the presence of a new taxon in the
Bauru Basin: Ibirania parva. The fully-grown somphospon-
dylous internal bone tissue associated with a high laminae
and fossae development, plus the absence of visible neuro-
central sutures in the axial remains, indicates a late onto-
genetic stage to the type and referred specimens of this
new taxon. Additional μCT scan and histological data from
holotypic materials also support this assignment (Type G
and H bone tissues, ranging from the HOS 13–14), ruling
out the possibility that the small size exhibited by Ibirania
parva specimens are due they belonged to immature indi-
viduals.
Phylogenetic analyses retrieved Ibirania parva deeply
nested in Saltasauridae, as a member of its less inclusive
clade Saltasaurinae and sister-group to the clade formed by
the Patagonian species Rocasaurus muniozi and Bonatitan
reigi. Some taxa included in Saltasaurinae are already known
by displaying a noticeable reduction on its body sizes, being
Ibirania parva the first identified as a nanoid taxon through
histological data.
The geological evidence from Vila Ventura fossil-bear-
ing sites allows us to infer the possible paleoenvironmental
and paleoecological dynamics from this ecosystem, which
was established there during the late Santonian to early
Campanian time-interval (Late Cretaceous). The scenario in
AMEGHINIANA - 2022 - Volume 59 (5): 317–354
348

question corresponds to a braided fluvial system of a flood-
plain, under the strong influence of well-marked seasonal-
ity and predominantly arid climate. This environment could
acquire peculiar ecophysiographic settings during the dry
seasons, causing different selective pressures in the resi-
dent biota. We propose that the presence of nanoid taxa
outside an insular environment may be explained by a prob-
able phyletic nanism trend.
The nanism observed in Ibirania parva is associated with
the evolution of an endemic fauna in response to the
stressed environment conditions of São José do Rio Preto
Formation, characterized by prolonged drought periods.
Ibirania parva represents the first unequivocal nanoid
titanosaur reported from South America at this point and
indicates the occurrence of nanism processes also in non-
insular environments driven by recurring climatic and
ecophysiographic patterns.
ACKNOWLEDGMENTS
We thank the following colleagues for allowing access to the
specimens deposited under their care: R. Machado, R. C. Silva
(MCT/DGM of CPRM-RJ), L. Barbosa, S. A. K. Azevedo (MN-UFRJ), S.
A. S. Tavares (MPMA), L. S. Paschoa (MPPC), T. S. Marinho, J. C. G.
Silva Jr., L. C. B. Ribeiro (CPPLIP-UFTM), J. C. Corral, J. Alonso (MCNA),
B. Madarieta (MVHMC-UPV), F. Ortega (UNED), J. Le Loeuff (MDE), G.
Garcia, X. Valentin (UP), S. Maidment, P. Barrett (NHM), and V.
Codrea (UBB). We are grateful to V. Zurriaguz (CONICET-URN), P.
Mocho (IDL-UL), D. Pol (CONICET-MEF), and J. A. Wilson Mantilla
(MP-UMICH) for providing photographs of important specimens and
whose comments and suggestions enhanced the conceptualization
of this manuscript. The authors are also indebted to S. Lages (UFMG)
for his reconstructions of the specimens studied here, to L. B. dos R.
Fernandes for her collaboration in collecting part of the fossil
material, and to P. Morgato for preparing the thin sections. CT scan
imagery was possible through the staff efforts of the Laboratório
Multiusuário de Processamento de Imagens de Microtomografia
Computadorizada de Alta Resolução (MZ-USP) and of the Labo-
ratório de Tomografia Computadorizada do Instituto Médico Legal
de São Paulo. We would like to acknowledge P. Saldiva, M. P. Santos,
E. Cardoso, and the rest of the FM-USP team for conducting the
fossil tomography. We are grateful to reviewers C. Griffin and C.
Woodruff and the editor J. A. Wilson Mantilla, whose comments and
suggestions greatly improved this paper. This work was supported
by scholarships from Coordenação de Aperfeiçoamento de Pessoal
de Nível Superior (CAPES - Financial Code #001 to BAN and AMG),
Conselho Nacional de Desenvolvimento Científico e Tecnológico
(CNPq fellow # 130.280/2018-6 to BAN and # CNPq 131.777/
2018-1 to TA), and by a research grant from Fundação de Amparo
à Pesquisa do Estado de São Paulo (FAPESP proc. 2011/50206-9
to HZ). The authors are also deeply grateful to Colecionadores de
OssosTM and their Crowdfunder’s, for supporting part of the costs
and analyses. The TNT software v1.5 was made freely available
through the Willi Hennig Society (http://www.lillo.org.ar/phylogeny/
tnt/). This paper was originally intended to be published in a special
volume of the Anais da Academia Brasileira de Ciências honoring
Diogenes De Almeida Campos but had to be withdrawn after final
acceptance due to technical issues. Nevertheless, we would like to
express our gratitude for the profound and enduring contribution
given by Dr. D. Campos to Brazilian Palaeontology.
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Editorial Note: Both this work and the nomenclatural acts it contains have been
regist ered i n the ZooBank . The work is permanently archived in the On line
Archives LOC KSS and Portico.
LSID urn:lsid:zoobank.org:pub:8B578EFC-D121-420C-AED8-5E836AC6E179
doi: 10.5710/AMGH.25.08.2022.3477
Submitted: 27 October 2021
Accepted: 25 August 2022
Published: 15 September 2022
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