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The largest Thalattosuchian (Crocodylomorpha) supports Teleosaurid survival across the Jurassic-Cretaceous boundary.



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The largest thalattosuchian (Crocodylomorpha) supports teleosaurid
survival across the Jurassic-Cretaceous boundary
Federico Fanti
, Tetsuto Miyashita
, Luigi Cantelli
, Fawsi Mnasri
, Jihed Dridi
Michela Contessi
, Andrea Cau
Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Alma Mater Studiorum, Universit
a di Bologna, Via Zamboni 67, 40126 Bologna, Italy
Museo Geologico Giovanni Capellini, Alma Mater Studiorum, Universit
a di Bologna, Via Zamboni 63, 40126 Bologna, Italy
Department of Biological Sciences, University of Alberta, Edmonton, T6G 2E9 Alberta, Canada
Ofce National Des Mines, Service Patrimoine G
eologique, 24 Rue de l'Energie 8601, La Charguia, 2035 Tunis, Tunisia
Museo Civico di Scienze Naturali Malmerendi, Via Medaglie d'Oro 51, 48018 Faenza, Italy
article info
Article history:
Received 18 July 2015
Received in revised form
5 November 2015
Accepted in revised form 15 November 2015
Available online xxx
Lower Cretaceous
A new teleosaurid from the Lower Cretaceous of Tataouine (Tunisia), Machimosaurus rex sp. nov.,
denitively falsies that these crocodylomorphs faced extinction at the end of the Jurassic. Phylogenetic
analysis supports its placement closer to M. hugii and M. mosae than M. buffetauti. With the skull length
up to 160 cm and an estimated body length of 10 m, M. rex results the largest known thalattosuchian, and
the largest known crocodylomorph at its time. This giant thallatosuchian probably was an ambush
predator in the lagoonal environments that characterized the Tethyan margin of Africa during the earliest
Cretaceous. Whether the Jurassic-Cretaceous mass extinction was real or artefact is debated. The dis-
covery of M. rex supports that the end-Jurassic crisis affected primarily Laurasian biota and its purported
magnitude is most likely biased by the incomplete Gondwanan fossil record. The faunal turnovers during
the J-K transition are likely interpreted as local extinction events, t riggered by regional ecological factors,
and survival of widely-distributed and eurytypic forms by means of habitat tracking.
© 2015 Elsevier Ltd. All rights reserved.
1. Introduction
The Jurassic-Cretaceous (J-K) transition has been considered a
complex phase of global extinctions in both terrestrial and marine
faunas, which affected rates of lineage diversication and
morphological evolution during the Early Cretaceous (Bakker, 1978,
1998; Sepkoski, 1984; Bardet, 1994; Benton, 2001; Upchurch and
Barrett, 2005; Lu et al., 2006; Benson et al., 2010). Whether this
event was real (i.e., a complex combination of clade-specic
extinction patterns driven by physical and biotic factors) or repre-
sents an artefact remains unresolved (Gasparini et al., 2004;
Bambach, 2006; Benson et al., 2010; Ruban, 2012; Newham et al.,
2014). Among speciose clades of Jurassic marine reptiles, tele-
osauroid crocodylomorphs stand as the sole that supposedly went
extinct at the Jurassic-Cretaceous boundary (Young et al., 2014a),
with all purported Cretaceous remains re-interpreted as belonging
to other reptilian clades, in particular, to the other thalattosuchian
clade, Metriorhynchoidea (Young et al., 2014a,b). From a palae-
ogeographic perspective, Teleosauroidea is known largely from
Europe (Vignaud, 1995), with Gondwanan remains rare, often
limited to problematic or extremely fragmentary specimens (e.g.,
Martin et al., 2015; Young et al., 2014a).
In December 2014, the articulated remains of a giant croc-
odylomorph were found during prospecting activities at the Touil el
Mhahir locality, Tataouine Governorate, Tunisia (Figs. 1, 2 ). In this
study, we describe this new specimen and determine its afnities
and stratigraphic placement. The results of our analyses support
the erection of a new species of thalattosuchian teleosaurid,
Machimosaurus rex. Furthermore, we discuss the implications of
this new African taxon in the debate on the end-Jurassic biotic
2. Material and methods
Specimens collected at the Touil el Mhahir locality in 2014 are
housed in the Mus
ee de l'Ofce National Des Mines (Minist
ere de
lIndustrie et de la Technologie, Tunis), under the accession
* Corresponding author. Dipartimento di Scienze Biologiche, Geologiche
e Ambientali, Alma Mater Studiorum, Universit
a di Bologna, Via Zamboni 67, 40126
Bologna, Italy.
E-mail address: (A. Cau).
Contents lists available at ScienceDirect
Cretaceous Research
journal homepage:
0195-6671/© 2015 Elsevier Ltd. All rights reserved.
Cretaceous Research xxx (2015) 1e12
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numbers ONM NG 1e25, 80, 81, and 83e87. Microvertebrate fossils,
eld notes and locality coordinates, and the 3D data are housed at
the Museo Geologico Giovanni Capellini (MGGC, Bologna, Italy).
Assemblage data were interpreted from the nal quarry map as
well as from eld notes: all elements were mapped using a 1 m
grid box. Following the discovery of small elements from the sur-
face of the outcrop, a total of 2.5 kg of sandy and clayish sediments
were collected from both the excavation site and the matrix sur-
rounding the skull for screen washing. Samples were soaked with
water and H
(5%) and screened using progressive sieves of
1 mm, 200
m, and 63
m. With 100% of collected matrix screened
and sorted, a total of 231 specimens were identied. The collected
specimens were primarily identied and compared with those
described and illustrated by Cuny et al. (2004), Cuny et al. (2010)
(Early Cretaceous of southern Tunisia), and Pouech et al. (2015)
(Berriasian of France). Furthermore, during the preparation of the
skull, four displaced osteoderms lying slightly imbricated on the
snout were recovered and prepared (ONM NG 14-17).
2.1. Taxonomy
The taxonomic content of the genus-level ranked clade Machi-
mosaurus von Meyer, 1837, is controversial. Young et al. (2014a,b)
recognised four species of Machimosaurus: M. buffetauti Young
et al., 2014b, M. hugii von Meyer, 1837, M. mosae Sauvage and
enard, 1879, (all from Europe) and M. nowackianus (von Huene,
1938) (from Ethiopia). Martin et al. (2015) challenged the distinc-
tion among the rst three species suggested by Young et al.
(2014a,b), referring all European Machimosaurus to M. hugii, and
considered M. nowackianus as a nomen dubium. We follow the
distinction among the species of Machimosaurus as suggested by
Young et al. (2014b) since both morphological and stratigraphic
disparities among the three European morphotypes support a
species-level distinction among them, and tested whether the in-
clusion of the new Tunisian material in a phylogenetic analysis of
Teleosauroidea further supports or challenges a taxonomic
distinction among the European Machimosaurus.
2.2. Phylogenetic analysis of Thalattosuchia
In order to analyse the evolutionary af nities of the Tunisian
thalattosuchian, we performed Bayesian inference methods inte-
grating the morphological and stratigraphic data with BEAST
(Rambaut and Drummond, 2009; Drummond et al., 2012) following
the method of Lee et al. (2014). The morphological dataset is based
on Young (2014) and modied by Cau (2014) after the a priori
exclusion of all non-thalattosuchian taxa. As branch duration esti-
mation and cladogenesis timing using Bayesian inference requires
sampling among both constant characters and autapomorphies of
terminal taxa e not solely among synapomorphies of internodes
(Lee et al., 2014) e
we retained all characters of the dataset of Young
(2014), including those resulted phylogenetically uninformative by
the a priori removal of most crocodyliform taxa from the ingroup.
The ingroup was consequently expanded by the inclusion of
Machimosaurus buffetauti (based on Martin and Vincent, 2013, and
Young et al., 2014b) and the new Tunisian thalattosuchian. One
Triassic pseudosuchian closely related to Crocodylomorpha (Post-
osuchus Chatterjee, 1985) and one basal crocodyliform (Protosuchus
Brown, 1934) were used as outgroups e with the former set as root
of the trees e according to the recent revision of thalattosuchian
afnities by Wilberg (2015) indicating a non-crocodyliform place-
ment for Thalattosuchia. Stratigraphic data and age constraints for
each terminal were obtained primarily from the Paleobiology
Database ( and from the literature, using
Fig. 1. (A) Geographic location and type locality of M. rex. (B) Simplied geological map of the Tataouine basin of southern Tunisia showing the Touil el Mhahir locality.
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provided geochronological ages for the formations in which the
taxa were found or the mean of the geologic stages associated with
those formations. The root age prior (i.e., the maximum age of the
last common ancestor of all included taxa) was set along a uniform
range between 218 Mya (the age of the oldest terminal included,
Postosuchus) and 252 Mya (the Permian-Triassic boundary). The
latter was considered as a loose hard constraint that consistently
pre-dates the age of the oldest potential crocodylomorphs and
basal loricatans. In the analysis, rate variation across traits was
modelled using the gamma parameter, and rate variation across
branches was modelled using an uncorrelated relaxed clock. The
analyses used four replicate runs of 40 million generations, with
sampling every 4000 generations. Burnin was set at 20%, and the
Maximum Clade Credibility Tree (MCCT) of the merged four post-
burnin samples was used as framework for phyletic reconstruction.
2.3. 3D photogrammetry and modelling
During the last decade, the development of Structure from
Motion (SFM) techniques has been dramatically improved allowing
accurate reconstruction of 3D structures processing 2D images
(Koenderink and Doorn, 1991; Beardsley et al., 1996; Trucco and
Verri, 1998; Dellaert et al., 2000; Haming and Peters, 2010; Fanti
et al., 2013; Engel et al., 2014; Fanti et al., 2015). We acquired dig-
ital models of the Machimosaurus quarry, the skull (both dorsal and
ventral views), and the prepared dorsal vertebrae, using high-
resolution photogrammetry. We used Agisoft PhotoScan Profes-
sional, and Meshlab for this technique. The models were built as in
the following procedure: 1. positioning of coded targets so that 70%
of photos frame at least one target (actual distances between tar-
gets will serve to include accurate measurement tools in the
model); 2. proper preparation of the light so that variations in the
enlightenment are minimal; 3. prearrangement of a photo-
shooting path. In order to properly perform the metric recon-
struction in the 3D model, it was mandatory to work with a camera
with a xed focal length lens. The lens prole for Agisoft Photoscan
was set using the software Agisoft lens. Automatic check of images
veried the complete coverage of selected objects before pro-
ceeding with the alignment of frames that originated the rst point
cloud based on corresponding points recognized in different
photos. Once the consistency of the generated surface were veri-
ed, a photographic texture was generated.
3. Stratigraphy and age
The Touil el Mhahir locality (the exact locality data can be ob-
tained upon request) is located less than 50 km to the south-west of
the city of Tataouine and about 25 km to the north-west of Remada
(Fig. 1). Substantial erosion resulted in a badland-like morphology
that exposed the basal beds of the Douiret Formation, and in
particular of the Douiret Sand Member. In the Tataouine Basin, the
Douiret Formation uncoformably overlays the Boulouha Formation
which has been assessed a Barremian age based on the occurrence
of the Cretaceous brachiopod Loriolithyris russillensis (De Loriol,
1866), in the upper beds of the unit (Peybernes et al., 1996; Ouaja
et al., 2004; Bodin et al., 2010). However, recent re-evaluation of
stratigraphic and biostratigraphic data in southern Tunisia and
western Lybia (Cuny et al., 2010; Le Loeuff et al., 2010; Fanti et al.,
Fig. 2. Machimosaurus rex quarry map. Ortographic images of the 3D photogrammetry-based model of the main quarry in natural light (A) and with superimposed collected
elements (B). Abbreviations: cv, cervical vertebrae; dr, dorsal ribs; dv, dorsal vertebrae; , forelimb bones; pe, pelvic elements; sk, skull; tp, turtle hyoplastron.
F. Fanti et al. / Cretaceous Research xxx (2015) 1e12 3
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2012) placed the lower, sandy deposits of the Douiret Formation in
the Barremian. Specically, the age of the Douiret Formation has
been assessed primarily through a detailed, basin-scale revision of
the stratigraphic occurrence and lateral variability of fossil-bearing
strata (Fanti et al., 2012). The occurrence of the hibodontid Eger-
tenodus Maisey, 1987, and Gyrodus Agassiz, 1833, in the Douiret
Formation supports an Hauterivian-Barremian age for this unit. In
fact, Rees and Underwood (2008) indicate the latest ascertain re-
cord of Egertenodus in the Barremian of Spain, and Kriwet and
Schmitz (2005) note the youngest record of Gyrodus in the Hau-
terivian of Germany. Therefore, although a pre-Hauterivian age of
the lower Douiret beds cannot be excluded, based on 1) the Early
Cretaceous age of the Boulouha Formation, and 2) stratigraphic and
biostratigraphic data provided by Cuny et al. (2010), Le Loeuff et al.
(2012), and Fanti et al. (2012), we conservatively consider the age of
the Touil el Mhahir locality as Hauterivian-Barremian.
The deposits are characterized by repeating, ning-up se-
quences of ne-grained sand and clay, capped by an alternating
sequence of clay and dolostone or dolomitized sandstone. The M.
rex quarry is located approximately 20 m above the fossil-rich
conglomerate that, on a basin scale, marks the base of the
Douiret Formation (Fanti et al., 2012). Furthermore, we report iso-
lated teeth of Machimosaurus sp. occurring in several localities from
the Douiret Formation deposits along the Dahar Escarpment (i.e. El
Hmaima, Jebel Haddada, Boulouha localities; Fanti et al., 2012)of
southern Tunisia, supporting that this genus is a representative of
this formation.
4. Taphonomy and paleoecology
The type specimen of Machimosaurus rex represents the rst
articulated vertebrate from the Douiret Formation and the second
Mesozoic archosaur skeleton collected in Tunisia (Fanti et al., 2012,
2013, 2015). The skeleton lies on its ventral side with the head
rotated clockwise toward the right side of the body (Figs. 2e4).
Only three teeth were found preserved in the alveoli (Fig. 5),
whereas seven were shed along the snout. Although preserved el-
ements show no evidence of major pre-burial transportation
(Figs. 2e8A), the overall posture (i.e. the body lying on its ventral
side and the head curved on the right side of the body) combined
with displacement of osteoderms and the missing anterior end of
the snout strongly suggest that there was some inuence from
paleocurrents (paleoow from the south-east). In addition, the
right side of the skull is laterally compressed (see also the tapho-
nomic model of Syme and Salisbury, 2014). The dorsal part of the
skeleton was found partially eroded with the exception of the skull,
which lay slightly below ground level. Large turtle plastron ele-
ments were collected near the skull (Fig. 7E). The skull, two dorsal
vertebrae, several dorsal rib and gastralia fragments, a partial hu-
merus and osteoderms were collected during the excavation. The
remaining part of the quarry was mapped and isolated elements
littering the ground were collected.
The M. rex holotype was collected in association with abundant,
disarticulated elements from large turtle carapaces, plastrons and
vertebrae. The largest turtle elements, including a 25 cm long
hyoplastron associated with the skeleton (Fig. 7E), suggest an in-
dividual close to 1 m in body length. Because most of the turtle
elements were slightly above the type skeleton of M. rex, these
elements can be attributed to a subsequent depositional event.
Microvertebrate remains are representative of brackish and marine
taxa and include elasmobranchs, actinopterygians, dipnoans and
rare pterosaur teeth. Bivalves, gastropods, fragmentary echinoids
shell and spines, and scaphopods are also abundant.
In terms of relative percentage, sh elements (teeth, scales and
centra) represent 71% of the isolated elements; crocodilian (teeth
and osteoderms) 10%; invertebrates (gastropods, bivalves, and
echinoderms) 4%; elasmobranchs 3%; and the remaining 12% con-
sists of unidentiable bony elements and teeth. Signicantly,
several teeth less than 5 mm in apicobasal length and a 4 mm wide
osteoderm are otherwise morphologically similar to those
described for Machimosaurus; the teeth are referred to the latter
taxon based on shared presence of blunt apex and anastomosing
apicobasal ridges on tooth crown. In addition, a partial dentary with
in situ teeth referable to a juvenile individual of Machimosaurus was
recovered in association with the type skull of M. rex. Prospecting
activities in the area revealed the presence of four additional
crocodylomorph individuals comparable in size and overall pres-
ervation to the M. rex holotype within 200 m from the main quarry.
The lower beds of the Douiret Formation are also rich in
megaplant remains, including large gypsied and sporadic hema-
tized trunks reaching 8 m in length. Remarkable fossil abundance in
the area and recurrent tree trunks indicate high rates of sediment
supply and accumulation: however, the lack of in situ plant roots
and organic components in the sediments combined with gypsied
fossils and dolomitized sandstones indicate arid to xeric environ-
ments subject to evaporitic conditions. Overall, facies analysis and
faunal assemblage are interpreted as a vast lagoonal system with
both marine and terrestrial inuences.
5. Systematic paleontology
Crocodylomorpha Hay, 1930
Thalattosuchia Fraas, 1901
Teleosauridae Saint-Hilaire, 1831
Machimosaurus von Meyer, 1837
Machimosaurus rex sp. nov.
(ZooBank code: LSID
Etymology. The species name rex, Latin for king, refers to its
majestic size among known
Machimosaurus and all
Holotype. ONM NG NG 1e25, 80, 81, and 83e87 (Figs. 2e7D;
Table 1).
Locality and horizon. Touil el Mhahir, Tataouine Governorate,
Tunisia; Douiret Sand Member, Douiret Formation, Hauterivian,
Lower Cretaceous.
Diagnosis. Teleosaurid differing from other species by unique
combination of: adult basicranial length >155 cm (Fig. 5); rostrum
ornamented by densely arranged, parallel longitudinal ridges; orbit
elliptical; interorbital space narrow (one f th length of skull pos-
terior to orbit); anteromedial margin of supratemporal fossae
round; frontal not extended anteriorly to orbit and with reduced
orbital margin; relatively large maxillary alveoli; anterior dorsal
neural spine height less than centrum height; dorsal osteoderms
with tightly packed pits that are round centrally and ellipsoid
Differential diagnosis. Among the genus Machimosaurus (Fig. 8),
M. rex differs from M. buffetauti (Fig. 8A) in having relatively larger
and more closely spaced alveoli, and in bearing apicobasally aligned
enamel ridges immediately adjacent to the apical anastomosed
region of crown teeth that are closely packed on both labial and
lingual sides; from M. hugii (Fig. 8C) in showing more developed
ornamentation on maxillae and nasals, elliptical orbits, narrower
interorbital space, and dorsal osteoderms with more closely spaced
pits that become more elongate peripherally; from M. mosae
(Fig. 8B) in bearing elliptical orbits and shallower and unkeeled
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ventral osteoderms. There is currently no overlapping material
between M. nowackianus and M. rex for a direct morphological
comparison. Although stratigraphic placement alone cannot be
used as a taxonomic criterion, based on stratigraphic separation
between the two type localities of M. nowackianus and M. rex (the
former is Oxfordian-Kimmeridigian in age, see Young et al., 2014b),
we consider likely these two African species as distinct.
6. Description of Machimosaurus rex type specimen
6.1. Skull and mandible (Figs. 3e7A)
The anterior end of the snout is missing. Based on comparison
with other specimens of Machimosaurus (Hua, 1999; Martin and
Vincent, 2013; Young et al., 2014a,b), we estimate that approxi-
mately posterior two thirds of the maxillae are intact. The pre-
served parts are ornamented with a dense pattern of lightly
developed longitudinal ridges (Fig. 5A). Eight alveoli are preserved
in the right maxilla (Fig. 5C). They are relatively large, their diam-
eter being up to one sixth of snout width, and are closely spaced
(Martin and Vincent, 2013; Young et al., 2014b). The interalveolar
space is regular, as in the mid- and posterior part of the maxilla of
M. hugii and M. mosae. The nasal is subtriangular in dorsal view and
ornamented by a nely developed pattern of longitudinal ridges. It
does not reach the narial region anteriorly. The periorbital region is
poorly preserved, with only fragmentary prefrontals and lacrimals
present. Nevertheless, the preserved outline indicates elliptical
orbits, more like that in M. buffetauti, differing from the more
quadrangular shape observed in both M. hugii and M. mosae (Young
et al., 2014b). The lateral margins of the orbits are at the level of the
anteromedial corners of the supratemporal fossae, relatively much
closely placed than in M. hugii (Young et al., 2014b, g. 41). The
nasofrontal suture is at the level of the anterior margin of the orbit.
The anterior end of the dorsal interfenestral bar is preserved, but
most of the bar, including the parietal, is lost. The anterior margin of
the supratemporal fossa is gently rounded. The posterior oor of
the supratemporal fossae is partially preserved. The postorbital is
robust and elongate posteriorly. Only the lateral part of both
squamosals is preserved. The occipital region of the skull is pre-
served in numerous fragments. Nevertheless, the occipital condyle
was preserved in situ, allowing an accurate estimation of the pre-
served basicranial length. The occipital condyle (Fig. 7A) consists
exclusively of the basioccipital, as in other species of Machimosau-
(Young et al., 2014b). The posterior ends of both dentaries are
preserved in articulation with the postdentary bones. The external
mandibular fenestra is elongate anteroposteriorly. Both the left and
right surangulars are articulated with the glenoid region. The an-
gulars are in fragments. The retroarticular processes are elongate
posteriorly and triangular in dorsal view. The teeth (Fig. 6)have
several diagnostic features for Machimosaurus (Young et al., 2014c).
The relatively low crowns are blunt apically and slightly curved
apicodistally. No carinae are present, suggesting that all preserved
teeth belong to the posterior half of the tooth row. The crowns are
ornamented with tightly packed ridges oriented apicobasally. As in
M. hugii, and differing from M. buffetauti (Young et al., 2014c), these
Fig. 3. Machimosaurus rex type skull, (A) dorsal view, (B) ventral view. Abbreviations: d, dentary; fr, frontal; lj, left jugal; la, lacrimal; mal, maxillary alveoli; mx, maxilla; na, nasal;
pa, palatal element; pdb, postdentary bones; posq, postorbital-squamosal bar; rap, retroarticular process; sa, surangular; stfo, oor of supratemporal fossa. Scale bar 50 cm.
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Fig. 4. Machimosaurus rex type skull, (A) in situ photograph showing dorsally exposed preserved bones, (B) prepared ventral surface. Abbreviations: fr, frontal; lj, left jugal; la,
lacrimal; ld, left dentary; lmx, left maxilla; lna, left nasal; lpd, left postdentary elements; lposq, left postorbitalsquamosal bar; os, osteoderm; pa, palatal element; rd, right dentary;
rmx, right maxilla; rna, right nasal; rpd, right postdentary elements; rposq, right postorbital-squamosal bar; stfo, oor of supratemporal fossa; tp, turtle plastron element. Scale
bar ¼ 50 cm.
Fig. 5. Detail of M. rex type snout in dorsal (A, B) and ventral (C, D) views. Abbreviations: d, dentary; dt, dentary tooth; fr, frontal; ju, jugal; la, lacrimal; lmx, left maxilla; na, nasal;
prf, prefrontal; rmx, right maxilla. Scale bar in C ¼ 5 cm.
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ridges are closely packed on both labial and lingual sides of the
crown. The ridges are irregularly undulated, but not producing
distinct pseudo-tubercles as in M. hugii (Young et al., 2014a,b). The
ridges are anastomosed in the apical third of the crowns, forming a
complex network as in other species of Machimosaurus. Most teeth
show a distinct (macroscopical) apical wear.
6.2. Postcranial skeleton (Figs. 2, 7BeD)
The cervical series is poorly preserved. Few fragments of the
atlas-axis complex were recovered adjacent to the occipital region
of the skull. Two well-preserved anterior dorsal vertebrae have
massive centra that are as wide as tall in anterior view (Fig. 7B). The
articular facet of the centra are subcircular and moderately concave.
The lateral surfaces of the centra are both dorsoventrally and
anteroposteriorly concave, due to the marked lateral rims of the
articular facets. The neural arch is transversely wide and low
dorsoventrally and has closely joined diapophyses and para-
pophyses that are oriented subhorizontally. The parapophyses
extend laterally to half the extent of the diapophyses, with their
articular surfaces facing posterolaterally. The dorsal surface of the
transverse process is anteroposteriorly convex. The ventrolateral
surfaces of the neural arches are moderately concave centrally. The
neurocentral suture is obliterated, suggesting a mature individual.
The zygapophyses are stout and moderately projected ante-
roposteriorly, being placed lateral to the neural canal and medial to
the centrum outline in anterior/posterior views. The neural spine is
robust, lower dorsoventrally than the height of the centrum and
moderately expanded transversally at its apex. Several dorsal ribs
and gastralia were found in articulation, although extremely
Appendicular elements include fragments of the left forelimb,
interpreted as the humeral shaft, and worn elements that, based on
in situ placement posterior to the dorsal ribs series, are interpreted
as belonging to the hindlimb.
6.3. Osteoderms (Fig. 7C, D)
Isolated osteoderms were found adjacent to the lower jaws. As
the skull is turned backward relative to the presacral vertebral
column, the osteoderms are interpreted as pertaining to the dorsal
region. The osteoderms are quadrangular, with poorly developed
anterolateral processes. Osteoderm ornamentation includes a
tightly packed pattern of rounded pits in the central part of the
dorsal surface, surrounded peripherally by radially elongate pits
that reach the margin of the osteoderm; this pitting pattern differs
from the more irregular pattern reported by Young et al. (2014b) for
Machimosaurus hugii. Furthermore, none of the recovered osteo-
derms bears the marked thickening and the distinct keel both
diagnostic of Machimosaurus mosae (Hua, 1999).
7. Results
7.1. Phylogenetic analysis
The MCCT of Thalattosuchia resulted by the Bayesian phyloge-
netic analysis (Fig. 9) agrees in overall topology with previous an-
alyses of the same dataset using parsimony as tree search strategy
(e.g., Young 2014). The analysis strongly supports the monophyly of
Machimosaurus (posterior probability: 97%) and the inclusion of the
new Tunisian taxon in that genus. Machimosaurus buffetauti
resulted the basalmost member of the genus, excluded from the
clade including M. rex and the other European species (posterior
probability: 63%). The analysis therefore supports the distinction of
M. buffetauti from other Machimosaurus suggested by Young et al.
(2014a). Cladogenetic timing estimated by the Bayesian analysis
places the divergence of the lineage leading to M. rex from the other
Machimosaurus lineages at about 155 Mya.
8. Size of
Machimosaurus rex
8.1. Skull length
The skull of the type specimen of M. rex lacks the anterior end of
maxillae and the premaxillae. The basicranial length of the pre-
served skull is 114 cm, the length of the preserved skull from the
Fig. 6. Dentition of M. rex type. Isolated tooth crowns in labial (A, D) and lingual (B, E)
views; (C) detail of enamel close to apex. Arrows indicate tubercle-like ornamentation
of ridges. Scale bar ¼ 5 cm.
Fig. 7. Skeletal anatomy of M. rex sp. nov. type specimen and associated turtle remains.
(A) Occipital condyle in dorsal view. (B) Anterior dorsal vertebra in anterior view.
(CeD) Osteoderms in dors al views. (E) Turtle hyoplastron in visceral view. Scale bars
AeD ¼ 5 cm; E ¼ 10 cm.
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anterior end to the left mandibular glenoid is 134 cm. The length of
the skull from occiput to the anterior end of the orbits (post-snout
length) is 65 cm. In a complete skull of M. buffetauti with a basi-
cranial length of 93.5 cm (Kimmeridgian, Germany; Martin and
Vincent, 2013; Fig. 8A), the equivalent part of the skull is 39 cm
long (42% of basicranial length). In other specimens of Machimo-
saurus, the snout length of the skull is approximately 58% of the
basicranial length, a value that is considered as an autapomorphy of
Machimosaurus (Hua, 1999; Young et al., 2014b; Fig. 8B). That im-
plies a 'post-snout' length of about 42% of the skull length in this
taxon (see also Martin and Vincent (2013), table 6). Assuming that
the proportions of the complete skull of M. rex holotype were
comparable to those observed in other Machimosaurus species, we
estimate a minimum total basicranial length for the Tunisian taxon
of 155 cm. Prior to this discovery, the largest size of Machimosaurus
was based on a fragmentary skull of M. hugii (the Leira specimen
of Young et al. 2014b, see Krebs (1967), Fig. 8C) with the basicranial
length estimated between 141 cm (Hua, 1999) and 149 cm (Young
et al., 2014b). Nevertheless, the Leira specimen lacks most of
the orbital and temporal regions, and no measurements of the
preserved elements are available, thus preventing any testable
estimation of its actual size (see Krebs, 1967).
A comparison between the size of the alveoli in M. rex type
specimen and other Machimosaurus individuals further supports
the giant size of the Tunisian taxon. In the skull of M. buffetauti type
specimen (Martin and Vincent, 2013), the mesiodistal diameter of
the alveoli at mid-length of the maxilla is between 15 and 18 mm.
In the neotype of M. mosae, the middle maxillary alveoli diameter
ranges between 18 and 25 mm (Hua, 1999). In the type specimen of
M. rex, the mesiodistal diameter of the middle maxillary alveoli
ranges between 30 and 43 mm, a value 200% or more than those of
M. buffetauti holotype, and about 166e173% larger than those in the
M. mosae neotype. The latter range con
rms that the basicranial
length of the Tunisian specimen is at least 166% larger than that of
the M. mosae neotype. Since the type skull of M. rex is also esti-
mated about 165e170% the size of the M. buf fetauti type skull
(Martin and Vincent, 2013), the Tunisian species shows propor-
tionally larger alveoli than in M. buffetauti.
8.2. Total body length
Young et al. (2014b) used the well-preserved neotype specimen
of M. mosae to estimate the total body length of various specimens
of Machimosaurus from their basicranial lengths, assuming a body
length to basicranial length ratio of about 6.22. Assuming isometry
among the various Machimosaurus individuals, and using the same
relationships of Young et al. (2014b), the total body length of M. rex
type is estimated at least as 9.6 m. Compared to the neotype of
M. mosae, the alveoli in M. rex holotype are about 166% larger than
the same element in the French specimen (Hua, 1999). Therefore,
assuming isometry in body proportions, based on both cranial and
dental comparisons with the best preserved specimen of Machi-
mosaurus mosae (Hua, 1999) the total body length of the Tunisian
Fig. 8. Comparison among skulls of Machimosaurus. (A) holotype of M. buffetauti, (B) neotype of M. mosae, (C) estimated size of the Leira specimen of M. hugii, (D) holotype of
M. rex. Dashed areas in (A) and (B) indicate size of largest known individuals of those species. (E) Reconstruction of M. rex body based on preserved elements. Figures (A)e(C)
modied from Young et al. (2014b).
F. Fanti et al. / Cretaceous Research xxx (2015) 1e128
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individual is estimated at about 10 m (166% of 6 m, see Young et al.,
2014b; Fig. 8E).
9. Discussion
9.1. Hypothetical lifestyle
The skull of M. rex bears a platyrostral snout, longitudinally
oriented ornamentations on the skull roof, elongate subrectangular
supratemporal fossae and blunt-crowned teeth with anastomosed
apical enamel ornamentation (Figs. 1, 2), all synapomorphies of
derived teleosaurids (Young et al., 2014b). With the skull length up
to 160 cm and an estimated body length around 10 m (Fig. 8E), the
new Tunisian species is the largest known thalattosuchian, and was
the largest known crocodylomorph from the Triassic until the
Aptian-Albian (see Young et al., 2014b, Johnson et al., 2015). As in
other Machimosaurus (in particular, M. hugii, Young et al., 2014b,c),
the low-crowned, sub-globidont dentition of M. rex supports a
generalist-durophagous feeding ecology. The abundance of turtle
remains in the M. rex quarry, including large-bodied forms with
length approaching 1 m, suggests that chelonians were a signicant
part of the diet also in the Tunisian taxon.
Krebs (1967) and Hua (1999) discussed the hypothetical life-
styles of M. hugii and M. mosae respectively (see also the review by
Young et al., 2014b). The former was interpreted as well-adapted to
an open sea environment, whereas the latter resulted better
adapted to high-energy, coastal conditions. Based on extant ana-
logues among crocodilians showing an inverse relationships be-
tween dermal ornamentation and aquatic adaptation, the relatively
reduced ornamentation in both skull roof and osteoderms of
Machimosaurus hugii has been suggested as additional functional
adaptation to a pelagic lifestyle (Young et al., 2014b). Similarly, the
thick and keeled ventral osteoderms of M. mosae are interpreted as
adaptations to a high-energy/turbulent environment (Hua, 1999;
Young et al., 2014b). In M. rex, both skull roof ornamentation and
extent of pitting on the osteoderms are more developed than in
M. hugii. The relatively shallower osteoderms lacking a keel suggest
that the Tunisian species was not adapted to a high-energy envi-
ronment as that inferred for M. mosae. This interpretation is
consistent with the paleoecology of the M. rex type locality (see
above) indicating a lagoonal environment with signicant terres-
trial inuences.
In analogy with modern semi-aquatic crocodilians, we suggest
that M. rex was an ambush predator that preyed on both aquatic
and terrestrial vertebrates. Since Machimosaurus bite marks on a
sauropod dinosaur bone are already known (
Young et al., 2014b),
we predict that M. rex included mid- to large-bodied dinosaurs in
its diet.
9.2. Implications for teleosaurid extinction
Unlike their survival into the Cretaceous of southern Tethys,
teleosaurids did not cross the J-K boundary in the northern realm
(Young et al., 2014a,b). The Late Jurassic species of Machimosaurus
occur from Portugal to Germany to Ethiopia in lagoonal to shallow
marine settings (Young et al., 2014b). These environmental condi-
tions existed well into Cretaceous times in southern Tunisia, where
lagoonal to tidal ats deposits straddle the J-K transition and
dominate the Lower Cretaceous sedimentary successions (Benton
et al., 2000; Barale and Ouaja, 2002; Ouaja et al., 2004; Anderson
et al., 2007; Ouaja et al., 2011; Fanti et al., 2012). Conversely, the
end-Jurassic transition in Europe is characterized by rapid climatic
oscillations (alternation of greenhouse conditions and cooling
events) and concomitant extension of pelagic environments with
dramatic loss of shallow marine and coastal ecosystems (Adatte
et al., 1996; Cecca, 1999; Cecca et al., 2001; Dromart et al., 2003;
ecuyer et al., 2003; Cecca et al., 2005; Husinec and Jelaska,
2006; Ruban, 2011; Martin-Garin et al., 2012). Reduction of these
habitats most likely resulted in local extinction of teleosauroids
across the J-K boundary of Europe. Among macropredatory marine
reptiles, as many as nine ichthyosaurian, three plesiosaurian and at
least four metriorhynchoid lineages crossed the J-K boundary, and
morphological disparity of these clades maintained the pre-
boundary levels through Early Cretaceous (Fischer et al., 2012,
2013, 2014; Benson and Druckenmiller, 2014; Young et al., 2014a;
Chiarenza et al., 2015). Our study adds teleosauroids to the list of
the reptilian lineages that crossed the Jurassic-Cretaceous
10. Conclusion
Machimosaurus rex sp. nov. is based on the articulated skeleton
of a giant crocodylomorph from the Hauterivian of Tunisia. This
taxon represents the rst indisputable Cretaceous teleosauroid, and
the rst member of this clade from Africa based on well preserved
remains. With a basicranial length approaching 160 cm (and a
partial skeleton indicating a total body length around 10 m), M. rex
is the largest known thalattosuchian. Both paleoecological data and
morphological features suggest that this species was an ambush
generalist predator with an ecology comparable to extant semi-
aquatic crocodilians. The discovery of M. rex falsies a global
mass extinction event at the J-K transition (i.e., teleosauroid
extinction), thereby highlighting the problem of sampling bias in
the reconstruction of large-scale patterns in the geological record.
The new Tunisian teleosaurid points to a conservative interpreta-
tion of faunal turnovers during the J-K transition: local extinction
events triggered by regional ecological factors and survival of
widely-distributed and eurytypic forms by means of habitat
Table 1
Selected measurements of Machimosaurus rex type specimen.
Measurements (cm)
Preserved basicranial length 114
Left side, from preserved anterior
end to mandibular glenoid
Right side, distance from mandibular
glenoid to anterior orbit
Width of snout anterior to orbits 25
Internal supratemporal fenestra length 33
Distance between ve maxillary alveoli 22
Estimated total length of maxillary tooth row (range) 80e97
Preserved snout length 49
Postorbital skull length 65
Interorbital width 11.5
Occipital condyle width 6.2
Anterior dorsal centrum height 8.5
Anterior dorsal vertebra total height 17.6
Anterior dorsal vertebra width across diapophyses 24.3
Maxillary Alveoli
1 29.6 35.2
2 29.5 28.8
3 34.4 28.2
4 32.6 26.1
5 33.6 29.9
6 43.4 34.7
7 38.9 29.9
8 n.d. 32.4
MD, mesiodistal diameter; LL, labiolingual diameter, in mm.
Numeration refers to position along the preserved maxilla and not to the
inferred position in the complete tooth row.
F. Fanti et al. / Cretaceous Research xxx (2015) 1e12 9
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This research was supported by the National Geographic So-
ciety (grant 9586-14), Museo Geologico G. Capellini (Bologna) and
Ofce National des Mines (Tunis). This manuscript beneted from
discussion with A.R. Fiorillo (Perot M useum of Nature and Science,
Dallas, U.S.A.). We thank S. Hua, M. Young a nd Editor in Chief E.
Koutsoukos for detailed revisions that improved the quality of the
manuscript. The Machimosaurus rex holotype was discovered by
FM dur ing prospecting activities led by FF, an d excavated by a
team including FF, JD, LC, AC and FM. The specimen was prepared
in Tunis by FF, FM, JD, LC, TM, and MC. AC and FF conceived and
wrote the manuscript, performed the analyses and prepared the
gures. TM, LC, MC, JD and FM helped draft the manuscript and
prepa re the gures. Skeletal reconstructions of M. rex are by M.
Auditore. We thank the other members of the 2014 Italian -
eTunisian palaeontological exp edition in the Tataouine Governa-
torate, in particular, H. Aljane, M. Hassine, L. Angelicola, A.
Bacchetta, S. Cafaggi, J. Carlet and G. Mignani . This study is dedi-
cated to the memory of Mounir R iahi, curator of the Mus
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Appendix A. Supplementary data
Supplementary data related to this article can be found at
F. Fanti et al. / Cretaceous Research xxx (2015) 1e1212
Please cite this article in press as: Fanti, F., et al., The largest thalattosuchian (Crocodylomorpha) supports teleosaurid survival across the
Jurassic-Cretaceous boundary, Cretaceous Research (2015),
... The oldest known African thalattosuchian is a poor remain recorded from the Toarcian strata of Madagascar (Buffetaut et al., 1981), and the one discovered in Bathonian deposits from the Taguelft Syncline in Morocco (Jouve et al., 2016), which confirms the presence of this group in North Africa during the Middle Jurassic. Also, the discovery of a teleosauroid in Tunisia in the Tataouine basin, confirms its extent in the early late Jurassic-early Early Cretaceous (Fanti et al., 2012(Fanti et al., , 2016. So, the discovery of a teleosauroid in the dolomitic limestones inside the Chaara Cave in Morocco dated from the earliest Jurassic is of an important order since it could be the oldest thalattosuchian record in Africa, and opens a very broad discussion on the stratigraphic distribution of Teleosauroids. ...
... In Africa, they are known in several localities from Tunisia, Ethiopia, Morocco, and Madagascar (Jouve et al., 2016;Dridi and Johnson, 2019). Most of the remains are fragmentary, and only three species have been named, Machimosaurus rex (Fanti et al., 2016), Machimosaurus nowackianus (Huene, 1938), and Steneosaurus baroni Newton, 1893, and the validity of the two latter could be questioned due to their poor preservation, and at least request a deep review. So, the discovery of new African remains is of particular importance. ...
... thalattosuchians cannot be currently evaluated as they were widely distributed as soon as the earliest Jurassic. During the last ten years, several thalattosuchians have been described from Africa (Fanti et al., 2016;Haddoumi et al., 2016;Jouve et al., 2016;Dridi and Johnson, 2019;Dridi, 2020). So, the relatively low number of thalattosuchian remains found in this continent could be related to preservation artifacts, or more probably, as tends to demonstrate recent findings, to an absence of adequate prospection of African localities (Jouve et al., 2016;Dridi and Johnson, 2019). ...
The Chaara cave is a natural karst cavity, located in the Middle Atlas of Morocco, shaped by water over millions of years. It is an active underground river, containing several galleries spread over two floors. The exploration of this cave led to the discovery of a teleosauroid crocodylomorph at the level of the dolomitic limestone of the earliest Jurassic (Hettangian-Sinemurian). A detailed paleontological study of the specimen's skull and nested mandible was carried out based on combinations of key morphological characteristics, but to the material does not allow an advanced assignment the Moroccan specimen to a genus level. A geological, topographical, and photogrammetric study was also carried out for the development of this discovery, which is a first in the region. A 3D model of the findings was made to reconstruct this finding. The extraction of the fossil is not possible, a molding was made to keep its imprint and allow its development as a paleontological heritage. Most known teleosauroids have been recovered from Europe, and they are particularly rare outside of Europe. In Africa, they are known from several localities in Tunisia, Ethiopia, Morocco and Madagascar. Most of the remains are fragmentary and only three species have been named, Machimosaurus rex, Machimosaurus nowackianus and Steneosaurus baroni. The temporal and geographical appearance of the first thalattosuchian in Africa remains highly discussed and not well understood thus, the discovery of new remains in Morocco in the dolomitic limestone of the earliest Jurassic is of great interest, as it represents the oldest known African thalattosuchian. It demonstrates that the geographical origin of thalattosuchians cannot currently be assessed because they were widely distributed as soon as the earliest Jurassic.
... Isolated pterosaur teeth from the lower Aptian Douiret Formation were alluded to by Fanti et al. (2016), with other vertebrates including elasmobranchs, actinopterygians, dipnoans and the teleosaurid Machimosaurus rex. These pterosaur teeth await formal description. ...
The Gondwanan pterosaur record is scarce when compared with that of Laurasia and is reviewed here. The majority of Gondwanan pterosaur remains are derived from South America; however, the relative richness of the South American record compared with other Gondwanan continents is largely a result of the ‘Lagerstätten’ effect. Nevertheless, the South American pterosaur assemblage represents the most speciose and diverse known from Gondwana, with several lineages represented, including the Raeticodactylidae, Rhamphorhynchoidea, Darwinoptera, Ctenochasmatidae, Gnathosaurinae, Nyctosauridae, Ornithocheiridae, Tapejaridae, Thalassodromidae, Dsungaripteridae, Chaoyangopteridae and Azhdarchidae. Gondwanan pterosauromorphs are known only from South America. From Africa rhamphorhynchids, archaeopterodactyloids, pteranodontians, nyctosaurids, ornithocheirids, tapejarids, dsungaripteroids, chaoyangopterids, and azhdarchids have been reported. The Arabian Peninsula has produced nyctosaurids, an istiodactyliform, ornithocheirids and azhdarchids. Non-pterodactyloid pterosaurs have been reported from India. A possible azhdarchid has been reported from Madagascar and rhamphorhynchids are known from isolated teeth. The Antarctic pterosaur assemblage also comprises isolated remains of indeterminate pterodactyloids, and a possible indeterminate rhamphorhynchoid. The pterosaur record from East Gondwana comprises ornithocheirids, azhdarchids and a possible ctenochasmatoid from Australia, as well as azhdarchids from New Zealand. Although our understanding of Gondwanan pterosaurs has greatly improved within the last three decades, the discovery and description of more specimens, particularly from Antarctica and East Gondwana, will enhance our understanding of pterosaurian biodiversity and palaeobiogeography.
... This is consistent with the situation of the most basal crocodyliforms with the bones preserved but not with Neuquensuchus universitas whose humerus is abnormally shorter than the ulna/radius (Fiorelli and Calvo 2007: figures 10 and 11). Many studies (such as Wu et al. 2001;Pol and Norell 2004;Pol and Gasparini 2009;Fiorelli et al. 2016;Arribas et al. 2019;Rummy et al. 2021;Ruebenstahl et al. 2022) considered Hsisosuchus as the sister group of the clade formed by Notosuchia/Ziphosuchia and the other mesoeucrocodylians while some of the others (such as Pol et al. 2013;Leardi et al. 2017) supported that Hsisosuchus just formed the sister group of the Notosuchia/Ziphosuchia within Mesoeucrocodylia. Many of notosuchians or ziphosuchians do not have the humerus and ulna/radius preserved. ...
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Hsisosuchus, with three known species, was the most common genus of crocodyliforms in the Sichuan Basin during the Jurassic. However, the overall shape of the ventral trunk shield of osteoderms has not been clarified due to the lack of complete specimens. A new specimen of Hsisosuchus recently recovered from the Upper Jurassic of Yunnan has the nearly complete ventral trunk shield preserved. This specimen provides an example for the first time for us to understand the shape and the way of the arrangement of the osteoderms in the ventral trunk shield in the genus. Compared with the articulated part of the ventral trunk shield preserved in two of the three species of the genus, the osteoderms of the ventral trunk shield of the new specimen are different in both shape and way of arrangement, indicating that the pattern of the ventral trunk shield is not constant within Hsisosuchus. With no skull and much of the postcranial skeleton poorly preserved as well as no corresponding element that can be used to compare with all the three species, the new specimen was considered as an indeterminate species of Hsisosuchus, awaiting more materials to clarify the problem.
... hugii was first described by von Meyer in 1837, in which he comments on the "…stumpfkonischen und dicht gestreiften Zähnen besonders charakteristisch herauszustellen…" ("…particularly (conspicuous in) conical and densely striped teeth…") (von Meyer, 1837: 560). More recently, multiple papers have highlighted and discussed machimosaurine features in great detail, including: the dentition Young et al. 2015a;Jouve et al. 2016); cranial features (Hua 1996;Fanti et al. 2016;Johnson et al. 2017;; pelvic bones (Johnson et al. 2017); and the unique sacral anatomy (Martin & Vincent 2013;Johnson et al., 2017). ...
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Johnson et al. (2020a) provided a comprehensive overview of Teleosauroidea, a diverse group of Mesozoic crocodylomorphs that lived in freshwater-to-marine ecosystems across the world. Johnson et al. (2020a) performed numerous phylogenetic analyses on Teleosauroidea and used them to establish a new taxonomic framework for this long-neglected clade. However, therein the numerous new teleosauroid clades were not properly registered in accordance with the International Code of Phylogenetic Nomenclature (PhyloCode). Herein we correct this error. We also replace the clade name Aeolodontinae with Aeolodontini, to ensure we do not inadvertently create two different names for this clade under the PhyloCode and the International Code of Zoological Nomenclature.
... In the years following 1996, many important paleontological discoveries prompted the ONM to commit, in 2014, to establishing the first Tunisian Geopark [45][46][47]. Since November 2015, the Geopark label has become a veritable UNESCO program, with the roadmap for establishing UNESCO Geopark elaborated within the convention ONM-Swisscontact [48]. In 2021, Tunisia's candidacy was retained (rank 2) because of the importance of the region's heritage potential (geological and cultural) within the framework of the UNESCO/GGN (Global Geoparks Network) initiative by ensuring the support of a certain number of initiatives for the "Aspiring Geopark" on the African continent by a customized and free accompaniment up to the submission of the candidature document. ...
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The concept of a UNESCO Global Geopark (UGGp) itself implies that the integration of geological, biological and anthropogenic factors and related values, both tangible and intangible, are at the base of any interpretation, communication, educative practices and enhancement aiming at strengthening the sense of place in local communities, as well as guiding those areas toward sustainable economic growth. However, the measures and good practices codified for UGGps limit their impact on the properties’ boundaries, sometimes neglecting the strong natural, social and cultural link between the listed areas, their surroundings and other serial geosites. The paper introduces a five-step study on selected examples of Geoparks and geosites in Italy, Japan and Tunisia, sometimes also including areas inscribed in the UNESCO list as cultural sites, focusing on the possible role of UGGps as drivers for sustainable development of geotourism. The research considers the contextualization of UNESCO UGGps within a broader territorial scale, introducing the concept of Diffused Geopark as a new opportunity in protection and management practices and as a driver for local economies and internationalization of lesser-known contexts.
... The fossil record of thalattosuchian crocodylomorphs from the Early Cretaceous, especially considering the recent discoveries (e.g., Fanti et al., 2016;Herrera et al., 2021), demonstrates that the generic compositions of the late Tithonian and Berriasian thalattosuchians were highly similar. The decline in species richness is suggested for this time interval (Tennant et al., 2016(Tennant et al., , 2017Herrera et al., 2021), but it is difficult to assess, given a still poor sampling from the earliest Cretaceous, compared to that from the Late Jurassic (Tennant et al., 2016;Young, Sachs, 2021). ...
Here we report the first ichthyosaurian finds from the Valanginian and Hauterivian of Austria. Based on their tooth morphology, they represent two distinct taxa with probably different feeding ecologies. The Valanginian specimen is a small tooth with a small crown and bulbous root, similar to teeth of Nannopterygius and Sisteronia - it likely was a soft-prey specialist or generalist. Hauterivian specimen has markedly larger teeth with more robust crowns indicating that it most likely occupied an ecological niche of a generalist. Although these specimens are not possible to determine at genus and species level, they demonstrate that two ichthyosaurian taxa inhabited the seas covering what is nowadays Austria in the Valanginian and Hauterivian. The present-day data on stratigraphic distribution of ichthyosaurian taxa at the Jurassic-Cretaceous transitional interval do not support the presence of marked events in the ichthyosaurian evolutionary history during the Tithonian–Berriasian times. Globally, Hauterivian ichthyosaurian taxa are quite different from Tithonian–Berriasian taxa. Therefore, an appreciable event in the evolutionary history of ichthyosaurians likely took place during the Valanginian, which is still extremely poorly characterized by ichthyosaurian fossils, hampering the assessment of the exact timing and severity of this event.
... Auch der wohl größte Fisch des Systems, Asthenocormus, war ein Filtrierer (Leich 2013;entgegen Janicke 1970 (Young et al. 2014a). Eine kreidezeitliche Art aus Tunesien brachte es sogar auf 10 m (Fanti et al. 2016 Im Jura waren große Pliosaurier weit verbreitet, scheinen aber das Solnhofener Archipel gemieden zu haben. Man kann spekulieren, dass geringe Wassertiefen hierfür verantwortlich waren. ...
... However, both major thalattosuchian lineages, the metriorhynchoids and teleosauroids, crossed the Jurassic-Cretaceous boundary (e.g., . The Cretaceous teleosauroid fossil record is problematic, and currently based on a single unambiguous occurrence from the upper Barremian of Colombia (Cortés et al. 2019; see also Fanti et al. 2016 and discussion in . In contrast, several metriorhynchoid lineages are known from Cretaceous deposits. ...
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Metriorhynchid crocodylomorphs were an important component in shallow marine ecosystems during the Middle Jurassic to Early Cretaceous in the European archipelago. While metriorhynchids are well known from western European countries, their central and eastern European record is poor and usually limited to isolated or fragmentary specimens which often hinders a precise taxonomic assignment. However, isolated elements such as tooth crowns, have been found to provide informative taxonomic identifications. Here we describe two isolated metriorhynchid tooth crowns from the upper Valanginian (Lower Cretaceous) of the Štramberk area, Czech Republic. Our assessment of the specimens, including multivariate analysis of dental measurements and surface enamel structures, indicates that the crowns belong to two distinct geosaurin taxa (Plesiosuchina? indet. and Torvoneustes? sp.) with different feeding adaptations. The specimens represent the first evidence of Metriorhynchidae from the Czech Republic and some of the youngest metriorhynchid specimens worldwide.
... The fossil records shows significantly higher historical diversity with a peak in Jurassic compared to the diversity of extant crocodilians (Bronzati et al. 2015). Previous studies have found evidence for the Triassic-Jurassic extinction (Markwick 1998) and the Jurassic-Cretaceous extinction (Tennant et al. 2016) although some debate of the true impact remains (Fanti et al. 2016). Most surprisingly, all previous studies assessed the impact of the K-Pg mass extinction as minor or non-existent (Markwick 1998;Brochu 2003;Bronzati et al. 2015;Mannion et al. 2015) although sister clades, such as non-avian dinosaurs and pterosaurs, with similar lifestyle (e.g., body size, habitat and food sources) and anatomy where severely impacted and went extinct 66 Mya. ...
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Crocodilians and their allies have survived several mass extinction events. However, the impact of the K-Pg mass extinction event on crocodylomorphs is considered as minor or non-existent although other clades of archosaurs, e.g. non-avian dinosaurs and pterosaurs, went extinct completely. Previous approaches using fossil occurrence data alone have proven inconclusive. In this paper, we take a phylogenetic approach using extant and extinct species. The time-calibrated phylogeny of extant crocodilians provides insights into the pattern of recent biodiversity changes whereas fossil occurrence data provide insights about the more ancient past. The two data sources combined into a single phylogeny with extinct and extant taxa provide a holistic view of the historical biodiversity. To utilize this combined data and to infer the impact of the K-Pg mass extinction event, we derive the likelihood function for a time-varying (episodic) serially sampled birth-death model that additionally incorporates mass extinctions and bursts of births. We implemented the likelihood function in a Bayesian framework with recently developed smoothing priors to accommodate for both abrupt and gradual changes in speciation, extinction and fossilization rates. Contrary to previous research, we find strong evidence for the K-Pg extinction event in crocodiles and their allies. This signal is robust to uncertainty in the phylogeny and the prior on the mass extinctions. Through simulated data analyses, we show that there is high power to detect this mass extinction and little risk of false positives.
From the Middle Jurassic to the Early Cretaceous, metriorhynchid crocodylomorphs inhabited marine ecosystems across the European archipelago. Unfortunately, European metriorhynchids are only well known from Germany, France, and the UK, with the Eastern European fossil record being especially poor. This hinders our understanding of metriorhynchid biodiversity across these continuous seaways, and our ability to investigate provincialism. Here we describe eleven isolated tooth crowns and six vertebrae referable to Metriorhynchidae from the Callovian, Oxfordian, Volgian (Tithonian), and Ryazanian (Berriasian) or Valanginian of European Russia. We also describe an indeterminate thalattosuchian tooth from the lower Bajocian of the Volgograd Oblast, the first discovery of a marine reptile from the Bajocian strata of European Russia. These rare fossils, along with previous reports of Russian thalattosuchians, indicate that thalattosuchians have been common in the Middle Russian Sea since it was formed. Palaeolatitude calculations for worldwide metriorhynchid-bearing localities demonstrate that the occurrences in European Russia are the most northern, located mainly between 44–50 degrees north. However, metriorhynchids appear to be rare at these palaeolatitudes, and are absent from palaeolatitudes higher than 50°. These observations support the hypothesis that metriorhynchids evolved an elevated metabolism but were not endo-homeothermic, especially as endo-homeothermic marine reptiles (ichthyosaurs and plesiosaurs) remained abundant at much higher palaeolatitudes.
Conference Paper
We propose a direct (feature-less) monocular SLAM algorithm which, in contrast to current state-of-the-art regarding direct meth- ods, allows to build large-scale, consistent maps of the environment. Along with highly accurate pose estimation based on direct image alignment, the 3D environment is reconstructed in real-time as pose-graph of keyframes with associated semi-dense depth maps. These are obtained by filtering over a large number of pixelwise small-baseline stereo comparisons. The explicitly scale-drift aware formulation allows the approach to operate on challenging sequences including large variations in scene scale. Major enablers are two key novelties: (1) a novel direct tracking method which operates on sim(3), thereby explicitly detecting scale-drift, and (2) an elegant probabilistic solution to include the effect of noisy depth values into tracking. The resulting direct monocular SLAM system runs in real-time on a CPU.
Conference Paper
Life on land today is as much as 25 times as diverse as life in the sea. Paradoxically, this extraordinarily high level of continental biodiversity has been achieved in a shorter time and it occupies a much smaller area of the Earth's surface than does marine biodiversity. Raw palaeontological data suggest very different models for the diversification of life on land and in the sea. The well-studied marine fossil record appears to show evidence for an equilibrium model of diversification, with phases of rapid radiation, followed by plateaux that may indicate times of equilibrium diversity. The continental fossil record shows exponential diversification from the Silurian to the present. These differences appear to be real: the continental fossil record is unlikely to be so poor that all evidence for a high initial equilibrial diversity has been lost. In addition, it is not clear that the apparently equilibrial marine model is correct, since it is founded on studies at familial level. At species level, a logistic family-level curve probably breaks down to an exponential. The rocketing diversification rates of flowering plants, insects, and other land life are evidently hugely different from the more sluggish rates of diversification of life in the sea, perhaps as a result of greater endemism and habitat complexity on land. Copyright (C) 2001 John Wiley & Sons, Ltd.
The Early Cretaceous of Tunisia has yielded rich shark assemblages in the Douiret Formation (Aptian), and both the Chenini Member and the Oum ed Diab Member (Albian) of the Aïn el Guettar Formation. These assemblages are very different from each other, suggesting different palaeoenvironments. The Douiret assemblage is dominated by hybodont sharks (Hybodus sp., Priohybodus arambourgi) with a marine ray ("Rhinobatos" sp.), suggesting a deposit very close to the coast, probably in a large tide-dominated delta. The Chenini assemblage is dominated by neoselachian sharks (Cretodus semiplicatus, cf. Protolamna, cf. Scapanorhynchus, Onchopristis dunklei) and a new species of the hybodont Tribodus, T. tunisiensis, indicating a shallow water marine environment and deposition probably somewhat farther from the coast than the Douiret Formation. On the contrary, the Oum ed Diab assemblage is devoid of neoselachians, strongly indicating a freshwater environment with no marine connection. Its hybodont fauna includes Hybodus sp. and Lissodus sp. as well as a new genus of Lonchidiidae, Diabodus tataouinensis.
The pelagic Jurassic successions of the Trapani region of western Sicily are dominated by the characteristic Tethyan Rosso Ammonitico lithofacies. In order to revise the stratigraphy (sedimentology, microbiofacies, ammonite and calpionellid biostratigraphy, isotope stratigraphy) and to define a reference section, a well exposed succession of Rosso Ammonitico, spanning the Callovian - Upper Berriasian interval, has been selected in the eastern sector of Monte Inici. Trapani province. A sedimentological study has enabled us to distinguish three subfacies within the Rosso Ammonitico: nodular, pseudo-nodular, and intraclastic nodular subfacies. The two latter subfacies are characterized by the presence of intraclasts produced largely by mechanical abrasion, that suggest a formation by hydrodynamic processes. Increasing hydrodynamic energy is inferred from Lower Kimmeridgian to Upper Berriasian deposits. The vertical evolution of the microfacies shows the greatest skeletal diversity in the Middle Oxfordian, coinciding with a peak of δ13C. Ammonites are abundant in the Middle Oxfordian - Lower Kimmeridgian, where several ammonite zones have been recognized. With the aid of calpionellids we have been able to identify the Jurassic - Cretaceous boundary and to recognized high frequency biostratigraphic intervals in the Berriasian, that can be correlated throughout palaoetethys. The δ13C curve shows a marked positive peak at the base of the section (Lower to Middle Callovian) and a second, composite, positive excursion in the Middle-Upper Oxfordian. From the base of the Kimmeridgian, δ13C values slowly decrease, remaining low in the Berriasian. Oxygen isotope values exclude late burial diagenetic overprinting and the carbon peaks are interpreted as reflecting carbon cycle perturbations due to high biological productivity that may mirror global palaeoenvironmental variations. The Middle Oxfordian peak coincides with the highest skeletal diversity, with the first occurrence of the nodular facies, and with the onset of cherty limestones (lateral equivalents of radiolarites) in the southern sector of Monte Inici, and in localities to the west and north. The heteropy between Rosso Ammonitico and radiolarites s.l. suggests that sedimentation was controlled by local palaeotopography.