A new primitive Neornithischian dinosaur from the Jurassic of Patagonia with gut contents

Abstract

We describe a new species of an ornithischian dinosaur, Isaberrysaura mollensis gen. et sp. nov. The specimen, consisting in an almost complete skull and incomplete postcranium was collected from the marine-deltaic deposits of the Los Molles Formation (Toarcian-Bajocian), being the first reported dinosaur for this unit, one of the oldest from Neuquén Basin, and the first neornithischian dinosaur known from the Jurassic of South America. Despite showing a general stegosaurian appearance, the extensive phylogenetic analysis carried out depicts Isaberrysaura mollensis gen. et sp. nov. as a basal ornithopod, suggesting that both Thyreophora and neornithischians could have achieved significant convergent features. The specimen was preserved articulated and with some of its gut content place in the middle-posterior part of the thoracic cavity. Such stomach content was identified as seeds, most of them belonging to the Cycadales group. This finding reveals a possible and unexpected role of this ornithischian species as seed-dispersal agent. Dinosaurs were present in most terrestrial ecosystems for 185 million years, interacting with their physical environment and other living organisms, including plants. As in modern ecosystems, there were complex ecological relations between plants and plant-eating organisms. However, there is little evidence of the type and the parts of plants on which different phytophagous dinosaurs fed 1–4. We describe a new species of ornithischian dinosaur with indubitable gut content consisting of a great amount of cycad and other plant seeds; this finding reveals that there were interactions between cycads and ornithischians in the dispersion of seeds.

Full text

1
Scientific RepoRts | 7:42778 | DOI: 10.1038/srep42778
www.nature.com/scientificreports
A new primitive Neornithischian
dinosaur from the Jurassic of
Patagonia with gut contents
Leonardo Salgado1, José I. Canudo2, Alberto C. Garrido3,4, Miguel Moreno-Azanza5,
Leandro C. A. Martínez6,7, Rodolfo A. Coria7,8 & José M. Gasca3,7
We describe a new species of an ornithischian dinosaur, Isaberrysaura mollensis gen. et sp. nov. The
specimen, consisting in an almost complete skull and incomplete postcranium was collected from
the marine-deltaic deposits of the Los Molles Formation (Toarcian-Bajocian), being the rst reported
dinosaur for this unit, one of the oldest from Neuquén Basin, and the rst neornithischian dinosaur
known from the Jurassic of South America. Despite showing a general stegosaurian appearance, the
extensive phylogenetic analysis carried out depicts Isaberrysaura mollensis gen. et sp. nov. as a basal
ornithopod, suggesting that both Thyreophora and neornithischians could have achieved signicant
convergent features. The specimen was preserved articulated and with some of its gut content place in
the middle-posterior part of the thoracic cavity. Such stomach content was identied as seeds, most
of them belonging to the Cycadales group. This nding reveals a possible and unexpected role of this
ornithischian species as seed-dispersal agent.
Dinosaurs were present in most terrestrial ecosystems for 185 million years, interacting with their physical envi-
ronment and other living organisms, including plants. As in modern ecosystems, there were complex ecological
relations between plants and plant-eating organisms. However, there is little evidence of the type and the parts
of plants on which dierent phytophagous dinosaurs fed1–4. We describe a new species of ornithischian dinosaur
with indubitable gut content consisting of a great amount of cycad and other plant seeds; this nding reveals that
there were interactions between cycads and ornithischians in the dispersion of seeds.
e holotype of Isaberrysaura mollensis gen. et sp. nov. is an incomplete articulated skeleton including an
almost complete skull and a partial postcranium from a medium-to-large-sized specimen (estimated length
5–6 m). is specimen was found in marine-deltaic levels of the Los Molles Formation from the Middle Jurassic
(Neuquén province, Argentina); in fact, these are the rst dinosaur remains found in this geological unit.
Isaberrysaura mollensis gen. et sp. nov. is the first neornithischian dinosaur from the Jurassic of South
America. Up to now, the South American record of Jurassic ornithischian dinosaurs was limited to just a few
specimens belonging to Heterodontosauriformes, a clade of small-sized forms that survived in Europe up to
the Early Cretaceous5–7. By contrast, the other major clade of ornithischians, the Neornithischia, was highly and
diversely represented in various Jurassic – above all Late Jurassic – localities in the world. Up to now, however, it
has been considered absent from the Jurassic localities of South America.
e material here described was found by Isabel Valdivia and Erico Otilio Berry in the locality of Los Molles
(Neuquén Province, Argentina, Fig.1) and brought, partially prepared, to the ‘Prof. Dr. Juan A. Olsacher’ Natural
Sciences Museum. In 2009 more eld work was undertaken, and further fragmentary material was collected.
1Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro-Conicet, Av. Gral. J. A.
Roca 1242, General Roca (8332), Río Negro, Argentina. 2Facultad de Ciencias-IUCA, Universidad de Zaragoza, C/
Pedro Cerbuna 12, 50009 Zaragoza, Spain. 3Museo Provincial de Ciencias Naturales “Profesor Dr. Juan A. Olsacher”,
Dirección Provincial de Minería, Etcheluz y Ejército Argentino, Zapala (8340), provincia del Neuquén, Argentina.
4Departamento Geología y Petróleo, Facultad de Ingeniería, Universidad Nacional del Comahue, Buenos Aires 1400,
Neuquén (8300), provincia del Neuquén, Argentina. 5Departamento de Ciências da Terra, Geobiotec. Departamento
de Ciências da Terra. Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-526. Caparica,
Portugal. 6Facultad de Ciencias Naturales y Museo, División Paleobotánica, Universidad Nacional de La Plata, Paseo
del Bosque S/N, La Plata (B1900FWA), Argentina. 7Consejo Nacional de Investigaciones Científicas y Técnicas,
Argentina. 8Museo “Carmen Funes”. Plaza Huincul (8318), Neuquén, Argentina. Correspondence and requests for
materials should be addressed to L.S. (email: lsalgado@unrn.edu.ar)
Received: 02 March 2016
Accepted: 16 January 2017
Published: 16 February 2017
OPEN

www.nature.com/scientificreports/
2
Scientific RepoRts | 7:42778 | DOI: 10.1038/srep42778
Results
Systematic palaeontology
Ornithischia Seeley, 1887
Genasauria Sereno, 1986
Neornithischia Sereno, 1986
Isaberrysaura mollensis gen. et sp. nov.
Etymology. In honour of Isabel Valdivia Berry, who reported the nding of the holotype material.
Holotype. MOZ-Pv 6459. A skeleton comprising a nearly complete skull, and a partial postcranium (still
unprepared) consisting of 6 cervical vertebrae, 15 dorsal vertebrae, a sacrum with a partial ilium and an appar-
ently complete pubis, 9 caudal vertebrae, part of a scapula, ribs, and unidentiable fragments.
Type locality and horizon. The holotype comes from the locality of Los Molles (Neuquén Province,
Argentina) (Fig.1). The specimen was found in the marine-deltaic deposits of the Los Molles Formation
(Toarcian-Bajocian), which in this sector reaches a thickness of approximately 1,042 m8. e fossil-bearing level
is composed of laminated pelites rich in ammonitiferous concretions and vertebrate remains, located some 40 m
below the contact with the overlying unit (Lajas Formation, Bajocian-Bathonian). e presence of the ammonite
Sonninia altecostata allows the fossil-bearing level to be situated biochronologically in the early Bajocian9. In
palaeoenvironmental terms, the sedimentary succession comprises a large-scale progradational deltaic system,
dominated by wave action and the inuence of storms10,11. e dinosaur remains described here, the rst reported
from this unit, are among the oldest from Neuquén Basin12.
Diagnosis. Isaberrysaura diers from all other ornithischian dinosaurs in the following autapomorphies: pre-
maxilla with posterolateral process that does not contact the lacrimal, elongated maxilla and correlated increase
in the tooth count and snout length, and the posterior process of the jugal at least as long as the anterior one.
e phylogenetic analysis revealed that this dinosaur also diers from all other ornithischians in the following
Figure 1. Geological map showing the type locality of Isaberrysaura mollensis gen. et sp. nov. e map was
made by Alberto C. Garrido on the basis of a LANDSAT satellite image available in the Dirección Provincial de
Minería (the institution where A.C.G. works) using Adobe Photoshop CS2 Serial Number: 1045-1412-5685-
1654-6343-1431.

www.nature.com/scientificreports/
3
Scientific RepoRts | 7:42778 | DOI: 10.1038/srep42778
combination of synapomorphies: two supraorbitals incorporated into the orbital margin (char. 32, from 0 to 1,
shared with Agilisaurus, Haya, escelosaurus and Pachycephalosauria), a broad contact between the postorbital
and the parietal (char. 51, from 0 to 1, shared with Pachycephalosauria), subcircular supratemporal fenestrae
(char. 66, from 0 to 1, shared with most ceratopsians), and an anteriorly downturned dentary row (char. 98, from
0 to 1, shared with yreophora).
Description. e skull of the new species is estimated to be 52 cm long and 20 cm wide across the orbits, and
it is almost as high as wide (Fig.2a–d). e snout slopes anteroventrally from the posterodorsal corner of the
infratemporal fenestra to what is apparently the maxillary-premaxillary contact. e infratemporal fenestra is
dorsoventrally deep (dorsoventral length = 13.5 cm, anteroposterior length = 7 cm). In contrast, the orbit is sub-
circular, not quite as dorsoventrally tall (~6.5 cm) as anteroposteriorly long (~7 cm), smaller than the infratempo-
ral fenestra, and only visible in lateral view (Fig.2c,d). e anterolateral sector of the le supratemporal fenestra
is relatively well preserved (although the bordering bones are mostly missing): it is visible only in dorsal view. e
antorbital fossa is roughly triangular, with its base longer than the other two sides. In absolute terms, it is some-
what anteroposteriorly shorter than the orbit, its dorsoventral height being ~3.7 cm.
e jugal is triradiate. Unlike all non-cerapodan neornithischians, escelosaurus, Hypsilophodon13, and
many basal iguanodontians, but similar to the condition in basal thyreophorans and stegosaurs, the anterior
process of the jugal forms the posteroventral corner of the antorbital fossa, and surpasses anteriorly the base of
the lacrimal, as in Emausaurus, Scelidosaurus and Huayangosaurus (Fig.2d). e anterior process is almost as
long as the posterior one (~7 cm). It is straight in lateral view, as in escelosaurus and basal thyreophorans and
unlike the neornithischians Agilisaurus and Zephyrosaurus, where the anterior process of the jugal is curved13.
In some basal thyreophorans (e.g., Scelidosaurus) and in stegosaurs (Huayangosaurus, Stegosaurus), the posterior
process is much shorter than the anterior one14. e dorsal process of the jugal is proportionally as long as in
Kulindadromeus and Hexinlusaurus, and shorter than in Agilisaurus15,16. In lateral view, the very broad quadra-
tojugal is observed.
Figure 2. Isaberrysaura mollensis gen. et sp. nov. holotype. Skull in dorsal (a and b, photograph and drawing
respectively), and le lateral (c and d, photograph and drawing respectively) views. (e) Premaxillary tooth;
(f,g) maxillary teeth (g inverted). amf, anterior maxillary fossa; aof, antorbital fossa; aso, anterior supraorbital;
d, dentary; ef, elliptical fossa; f, foramina; fr, frontal; i, infratemporal fenestra; j, jugal; mx, maxilla; n, nasals;
o, orbit; pd, predentary; pdb, postdentary bones; pmx, premaxilla; po, postorbital; pso: posterior supraorbital;
prf, prefrontal; qj, quadratojugal; sq, squamosal; stf, supratemporal fenestra. 1–7 denticles. e drawings were
processed using Adobe Photoshop CS2 Serial Number: 1045-1412-5685-1654-6343-1431.

www.nature.com/scientificreports/
4
Scientific RepoRts | 7:42778 | DOI: 10.1038/srep42778
e nasals are ~20 cm long. ere is a deep elliptical fossa along the presumed sutural contact of the nasals,
although the actual suture line cannot be seen (Fig.2a,b), a character that is present in a wide variety of dino-
saurs (Herrerasaurus, Changchunsaurus, Jeholosaurus, Haya, Agilisaurus, Stegosaurus, Heterodontosaurus and
Hypsilophodon). According to some authors17, thyreophorans lack such a fossa apomorphically, although others16
described in Huayangosaurus a shallow median depression on the dorsal aspect of the nasals.
There are two supraorbital bones in Isaberrysaura mollensis gen. et sp. nov. The anterior supraorbital is
elongated (~10 cm), as in stegosaurs, and rod-like, as in basal ornithischians18 (Fig.2c,d). e other element
interpreted as a posterior supraorbital is located on the posterior margin of the orbit. ere is another bone sur-
rounding the orbit that is possibly part of the anterior ramus of the postorbital, broken and displaced (Fig.2c,d).
e postorbital forms most of the posterior margin of the orbit. Its jugal process surpasses ventrally half of the
orbit; it has nearly the same width as the postorbital process of the jugal. e lacrimal is anterodorsally projected;
it is rather slender, above all in its contact with the jugal. Dorsally, it contacts with the nasal, the prefrontal (mostly
visible in dorsal view), and the anterior supraorbital, whereas anteriorly it articulates with the nasals and, appar-
ently, with the maxilla. e lacrimal forms the posterior and posterodorsal margins of the antorbital fossa pretty
much all ornithischian which retain an antorbital fenestra.
e premaxilla is incompletely preserved. It is robust, and the lateral surface of the oral margin is everted, as
in the neornithischians escelosaurus, Agilisaurus, Changchunsaurus, Orodromeus, Oryctodromeus, Talenkauen
and some basal iguanodontians13.
e posterolateral process of the premaxilla does not extend far enough posteriorly to contact the lacrimal,
as in basal ornithischians and thyreophorans, and unlike Heterodontosaurus, Jeholosaurus, the basal ceratopsians
Liaoceratops and Yinlong, and basal iguanodontians such as Tenontosaurus13.
It has at least six premaxillary teeth (three complete, two broken, and the mold of a sixth one), as in the basal
ornithischian Lesothosaurus, the basal thyreophoran Scutellosaurus, and the neornithischians escelosaurus
neglectus and Jeholosaurus13. In the anterior part of the snout, the posterodorsal process of the premaxilla is
observed. is part of the premaxilla is broken, but this process seems to wedge into a recess of the nasal, or in
between the nasal and maxilla. e premaxillary teeth are conical and slightly asymmetrical, and point poste-
riorly, somewhat lingually. e labial side is convex whereas the lingual side is only slightly convex. e crown
is globose and has a constriction in the neck (Fig.2e). e surface of the enamel is ornamented with parallel
longitudinal crests, many of which are anastomosed. ese seem to be more pronounced in the anterior teeth,
which are also the most globose. Ornamentation is present (though less developed) in escelosaurus, and absent
in Changchunsaurus, Jeholosaurus, Zephyrosaurus, Scelidosaurus and Emausaurus13. Unlike the maxillary teeth, a
pattern of replacement is not observed in these teeth. Unlike Agilisaurus and Huayangosaurus there are no den-
ticles in the premaxillary teeth15.
Unlike all neornithischians except Agilisaurus, but similar to the condition in basal thyreophorans like
Emausaurus and Scelidosaurus, there is no diastema between the premaxillary and the maxillary tooth row13.
e maxilla of Isaberrysaura mollensis gen. et sp. nov. is anteroposteriorly broad. ere is an anteroposterior
ridge causing the tooth row to be inset medially, as in escelosaurus, Lesothosaurus and Scutellosaurus and other
basal thyreophorans and basal neornithischians13.
On its lateral surface there are at least ve foramina dorsal to the tooth row. e dorsoventral depth of the
buccal emargination decreases anteriorly, which is an ornithischian synapomorphy according to character 26 of
Butler et al.17. Anteriorly, it is 0.6 cm in depth (measured from its border to the margin of the alveolus), whereas
at the level of the last alveolus it is almost 3.1 cm. In this respect, Isaberrysaura mollensis gen. et sp. nov. resembles
Stegosaurus. ere is a small depression in the anterior border of the maxilla, near the suture with the premaxilla,
much like that present in Changchunsaurus, Haya, Hypsilophodon, Jeholosaurus, Orodromeus, Zephyrosaurus13
and Huayangosaurus14. is depression is here interpreted as the anterior maxillary fossa13. As in other genera
(Huayangosaurus, ZDM7001; escelosaurus, NCSM 15728), the oor of the fossa seems to be formed by a ange
of the premaxilla13,14.
e maxilla has at least 30 tooth positions. In Scelidosaurus (BMNH R1111) there are 19; in escelosaurus
20; in Agilisaurus 14; in Emausaurus 21; in Stegosaurus 24, and 27–28 in Huayangosaurus14,15,19. e maxillary
teeth are closely packed, without space between the alveolar margin and the adjacent crown. ey are lanceolate,
partially imbricate and slightly curved distally, as a result of which they are asymmetrical in labial view (Fig.2g).
ey have 5 to 7 large denticles with an angle of 45°. ey present a slight eminence at the base of the tooth crown,
much less developed than in Scelidosaurus. e enamel surface is smooth. e anteriormost maxillary teeth are
somewhat smaller than the posterior ones and are slightly twisted anteriorly (Fig.2f).
Gut contents. One of the most notable features of the discovery of the skeleton belonging to Isaberrysaura
mollensis gen. et sp. nov. is that inside the skeleton there was a mass of permineralized seeds in the
middle-posterior part of the thoracic cavity (Fig.3f). ere is little direct evidence of the feeding habits of her-
bivorous dinosaurs that matches the stomach contents preserved within a carcass1,20. Most unaltered gut contents
in plant-eating dinosaurs are found in hadrosaurid ornithopods2, whereas until now there has been no known
record in basal neornithischians. Two types of seeds were recovered close to the posterior ribs of Isaberrysaura
mollensis gen. et sp. nov., distinguished according to their size. e largest seeds preserved three layers: an outer
eshy sarcotesta, the sclerotesta, and the inner layer (possibly corresponding to the nucellus). ese seeds are
assigned to the Cycadales (Zamiineae) on the basis of a well-dened coronula in the micropylar region, whereas
the smaller, platyspermic seeds are still indeterminate.
e largest fossil seeds were found with an entire sarcotesta, suggesting that they were gobbled down, and not
chewed. is is consistent with the morphology of the maxillary teeth of Isaberrysaura mollensis gen. et sp. nov.
and analogous with some living tetrapods (e.g. elephants and peccaries), which eat the seeds of cycads but avoid
masticating them3. e sarcotesta is a so tissue that is normally digested, but the sclerotesta is a hard tissue that

www.nature.com/scientificreports/
5
Scientific RepoRts | 7:42778 | DOI: 10.1038/srep42778
ensures safe passage of the endosperm through the digestive tract; this germinative strategy has been proposed
for the seeds eaten by some dinosaurs3,4. e well-preserved mass of seeds with a sarcotesta, clustered close to the
ribs, suggests that the digestion in the holotype specimen of Isaberrysaura mollensis gen. et sp. nov. was in its rst
steps in the gut.
Extant cycads produce harmful toxic compounds (e.g. cycasin), storing them in stems, leaves and seeds.
The sarcotesta in these cases contains high levels of toxins21; however, the sarcotesta is edible, especially
for large-bodied animals such as dinosaurs. The microbial “gut flora” of these reptiles probably contained
micro-organisms that produced active enzymes capable of cleaving the cycad molecule cycasin3,4,21. e seeds
with a thick sclerotesta would then pass through the digestive system, to be excreted as seed kernels. ese nd-
ings suggest the hypothesis of interactions (endozoochory) between cycads and dinosaurs, especially in the dis-
persion of seeds.
Isaberrysaura mollensis gen. et sp. nov. shows marked heterodonty. e possession of recurved premaxillary
and lanceolate maxillary/dentary teeth in extant iguanid lizards is correlated with diets that include a mixture of
animal and plant material22. However, the stomach contents of Isaberrysaura are composed entirely of seeds, with
no evidence of animal remains.
Phylogenetic analysis. Butler dataset, Godefroit et al. version. is analysis resulted in 1740 most parsi-
monious trees of 603 steps (consistency index 0.421, retention index 0.688).
As in most previous analyses of this dataset17,23–25, the resulting consensus is an uninformative polytomy.
Reduced consensus trees were obtained using the “tree-pruning” option of TNT, a posteriori removing wildcard
taxa, following the original approach in the rst iterations of this dataset17,23,24, by contrast with other analyses,
where certain taxa were removed a priori, on the basis of previous analyses16. Given the intricate puzzle that
ornithischian phylogeny currently represents, we consider that a priori removal of taxa, although it certainly
Figure 3. Gut content of Isaberrysaura mollensis gen. et sp. nov. (a–c), seeds of cycads (c), and other seeds (s);
rib (r). (d,e) Detail of seeds of cycads: sarcotesta (sa), sclerotesta (sc), coronula (c), nucellus (n). (f) Location
of the gut content in the reconstructed skeleton of Isaberrysaura mollensis gen. et sp. nov. e drawings were
processed using Adobe Photoshop CS2 Serial Number: 1045-1412-5685-1654-6343-1431.

www.nature.com/scientificreports/
6
Scientific RepoRts | 7:42778 | DOI: 10.1038/srep42778
increases the resolution of the consensus, can lead to important omissions in the phylogenetic relations of this
clade, and may result in the misidentication of clade synapomorphies. Using the “tree-pruning” option of TNT,
we searched for reduced consensus obtained aer pruning up to 5 taxa. From the multiple sets of ve taxa recov-
ered, we chose to prune Echinodon, Anabisetia, Koreanosaurus, Yueosaurus and Albalophosaurus a posteriori. e
reduced consensus tree gained 10 nodes, and recovered Isaberrysaura at the base of Neornithischia, in a trichot-
omy with Kulindadromeus and all more derived neornithischians (Fig.4). It shares with all ornithopods the pres-
ence of more than six sacral vertebrae (char. 137, from 2 to 3), a character also shared with some heterodontosaurs
and many stegosaurs and ankylosaurs.
Enforcing Isaberrysaura within yreophora resulted in 1140 equal-length trees of 607 steps (consistency
index 0.418, retention index 0.684). These trees recovered Isaberrysaura as the sister group of
Ankylosauria + Stegosauria, and are 4 steps longer than the unconstrained most-parsimonious trees. To test the
signicance of this result, 1000 replications of the Templeton test were used, comparing pairs of unconstrained
and constrained trees chosen at random from both tree spaces. All tests produced non-signicant results (see
SupplementaryInformation,C5), implying that the hypothesis of Isaberrysaura being a basal thyreophoran can-
not be rejected with condence.
Butler dataset, Baron et al. version. This analysis resulted in 69 most parsimonious trees of 594 steps
(Consistency index 0.428, retention index 0.689).
Again, the strict consensus shows a huge polytomy. To improve resolution, ve taxa were a posteriori pruned
from the consensus (Echinodon, Anabisetia, Yandusaurus, Yueosaurus and Koreanosaurus). e resulting topol-
ogy mimics that obtained by Baron et al.26, with the inclusion of Isaberrysaura among the basal neornithischi-
ans, more derived than Hexinlusaurus but less derived that Othnieliosaurus (SupplementaryFig.S1). Despite the
addition of Laquintasaura and the mergin of Lesothosaurus and Stormbergia carried by Baron et al.26, resulting in
a better characterization of the yreophora clade, Isaberrysaura remains immobile in its ornithopod placement.
Enforcing Isaberrysaura within yreophora resulted in a total of 7776 trees of 598 steps (consistency index 0.425,
retention index 0.686); four steps longer than the most parsimonious trees. Noticeably, the consensus of the con-
strained trees does not recover yreophora, which is collapsed into a big politomy together with Isaberrysaura,
Figure 4. Phylogenetic position of Isaberrysaura mollensis gen. et sp. nov. Calibrated reduced strict
consensus obtained aer including the Argentinian taxon in the current iteration of the Butler et al.17 dataset.
Numbers over branches are Bremer support values over 1. Numbers below branches represent bootstrap
support values over 50.

www.nature.com/scientificreports/
7
Scientific RepoRts | 7:42778 | DOI: 10.1038/srep42778
Lesothosaurus, Emasaurus, the Ankylosauria plus Stegosauria clade and the Ornithopoda clade. Again, 1000 rep-
lications of the Templeton test failed to reject this topology (SupplementaryInformation,C5).
Boyd dataset. A total of 180 most-parsimonious trees of 889 steps were obtained (consistency index 0.359, reten-
tion index 0.660). e resulting topology of the strict consensus resembles that published by Boyd27, with some
important exceptions. Isaberrysaura is recovered as belonging to Parksosauridae, the sister group of Cerapoda,
but its location within this clade remains uncertain (SupplementaryFig. S2). e inclusion of Isaberrysaura
results in the collapse of both Orodrominae and escelosaurinae subfamilies into a polytomy. Isaberrysaura is
placed in a variable basal position within escelosaurinae or as a sister taxon of the clade containing Orodromeus
and the unnamed taxon from Kaiparowits. Isaberrysaura diers from all Parksosauridae in the absence of a dias-
tema between the premaxillary and maxillary teeth (char. 8, from 1 to 0), and shares with them the everted lateral
surface of the oral margins of the premaxilla (char. 5, from 0 to 1, also shared with Agilisaurus), the concavity of
the posterior end of the premaxilla for receipt of the anterolateral boss of the maxilla (char. 14, from 0 to 1) and
the presence of fused premaxillae (char. 255, from 0 to 1).
Enforcing Isaberrysaura within yreophora resulted in 72 equally parsimonious trees of 894 steps (consist-
ency index 0.357, retention index 0.657), ve steps longer than the most parsimonious placement of Isaberrysaura
within Parksosauridae. Isaberrysaura is recorded in a polytomy at the base of yreophora, in an unresolved
position between Scutellosaurus, Lesothosaurus and the clade formed by Emausaurus and Scelidosaurus. It is
important to note that in this topology no synapomorphies support the clade yreophora, due to the enforced
placement of Isaberrysaura, which indeed diers from all other thyreophorans in possessing a ventrally deected
margin of the premaxilla at the level of the maxillary teeth (char. 6, from 0 to 1, shared with Heterodontosauridae,
Orodromeus, Hypsilophodon and Zalmoxes) and in possessing a pubic peduncle of the ilium that tapers distally
and is smaller than the ischial peduncle (char. 192, from 0 to 1, shared with all neornithischians but Agilisaurus).
Again, 1000 replications of the Templeton test confronting the two topologies do not rule out the hypothesis of
Isaberrysaura being a thyreophoran (see SupplementaryInformation,C5).
Remarks. Isaberrysaura mollensis gen. et sp. nov. has been included in three dierent datasets, all of three recov-
ering it at the base of Ornithopoda. Despite the general stegosaurian appearance of the specimen, and presenting
an anteriorly downturned dentary row, a synapomorphy of yreophora, the extensive analysis carried out does
not allow us to consider the Neuquenian species as a basal member of this clade. Further preparation of the type
specimen, ndings of additional specimens and, above all, a better and more compressive dataset focused in the
basal thyreophorans may alter this results in the near future, and seed light on the Isaberrysaura puzzle: was it a
stegosaurian mimic ornithischian, with a skull shaped to prot similar vegetal resources as derived thyreophorans
or it is a very basal form of the thyreophoran clade?
Discussion
e discovery of the new basal neornithischian Isaberrysaura mollensis reveals the existence of a previously
unknown morphotype among basal neornithischians. e cranium of this new species is reminiscent of that
of the thyreophorans. Among the characters shared with the latter are their large body size, their elongate and
low skull (as occurs in stegosaurs, Emausaurus), at least six premaxillary teeth (6–7 being common in many
thyreophorans, but infrequent outside yreophora), the high maxillary tooth count (as in Huayangosaurus), the
depression between the premaxilla and maxilla (as in Huayangosaurus), the very deep buccal emargination (also
found in stegosaurs), and the anteriorly downturned dentary tooth row (a thyreophoran synapomorphy). e
interpretation given here is that Isaberrysaura and the thyreophorans were convergent forms of ornithischians.
Like thyreophorans in general and the basal stegosaurs in particular, Isaberrysaura shows weak or non-existent
wear facets, indicating a lower degree of oral food processing. is in turn is consistent with the state of the seeds
found in the digestive tract.
Although the reason for the many similarities between Isaberrysaura and the thyreophorans could have been
the diet they had in common, we still lack a clear idea of the diet of these dinosaurs beyond their ingestion of
cycad seeds and other seed plants. We conjecture that the summer diet consisted mainly of fructications, but
we remain completely ignorant of what food resources were used in periods when the seeds were unavailable.
e palaeobotanical association of conifers (Podocarpaceae, Araucariaceae and Cheirolepidiaceae), Cycadales,
Bennettitales and ferns from the Middle Jurassic of Neuquén Basin suggests humid-temperate to warm cli-
mates28–31. ese plants would belong to forest to open environments; such a diversity of environments with a rich
ora would have yielded enough food resources for the development of Isaberrysaura and the associated fauna.
e central and southern sector of Neuquén Basin was invaded by the waters of the Pacic Ocean from the
Pliensbachian (Lower Jurassic) to the Lower Cretaceous, interrupted only by brief periods of continentalization32–34.
e deposition of the Los Molles Formation was associated with the rst major ooding of the basin, with the
development of low-energy marine facies in restricted environments decient in oxygen, grading towards the far
south of the basin into the deltaic, shallow marine and estuarine deposits of the Lajas Formation10,11,35–39. To date,
no outcrops of a clearly continental origin providing terrestrial vertebrate remains have been found for this period
(Pliensbachian-Bathonian) in Neuquén Basin, so the discovery of this new ornithischian certainly contributes to our
knowledge of the Jurassic dinosaur faunas of Patagonia, known above all from Late Jurassic forms.
Methods
To assess the phylogenetic position of Isaberrysaura, it was coded in the three largest datasets availa-
ble in the literature: two dierent versions of the matrix built by Butler et al.17, one aer Makovicky et al.23,
Ruiz-Omeñaca et al.24, Barrett et al.25 and Godefroit et al.16 (SupplementaryInformationC1), and the other

www.nature.com/scientificreports/
8
Scientific RepoRts | 7:42778 | DOI: 10.1038/srep42778
aer Ham et al.40, and Baron et al.26, (SupplementaryInformationC2); and the dataset published by Boyd27
(SupplementaryInformationC3).
Butler dataset, Godefroit et al. version. e Butler dataset includes a total of 57 taxa scored for 227
characters, ve of which (112, 135, 137, 138, 174) were treated as ordered (see SupplementaryInformation). e
resulting dataset was analysed with TNT v1.5v41. A heuristic search with 1000 replicates, followed by branch
swapping by tree-bisection-reconnection (TBR), holding ten trees per replicate, was conducted. Additional
rounds of TBR were performed, obtaining increasing numbers of trees (up to two million), but no impacts on
the topology of the consensus were observed other than increasing computing times, so all the following analyses
were performed with the rst set of trees.
Butler dataset, Baron et al. version. The second version of Butler’s dataset includes a total of
55 taxa scored for 227 characters, five of which (112, 135, 137, 138, 174) were treated as ordered (see
SupplementaryInformation). Following Baron et al.26, 100 replications of new technology searches, including
sectorial searches, ratchet, dri and tree fusing algorithms were carried under default settings, followed by and
additional round of TBR using the obtained trees as starting seeds.
Boyd dataset. Isaberrysaura was also coded in the dataset by Boyd27 for a total of 69 taxa coded for 255 char-
acters (see SupplementaryInformation). A heuristic search with 1000 replicates, followed by branch swapping
by tree-bisection-reconnection (TBR), holding ten trees per replicate, was conducted. is was followed by an
additional round of TBR using the obtained trees as starting seeds.
Constrained searches. To explore the alternative hypothesis of Isaberrysaura being a thyreophoran, con-
strained searches were conducted enforcing the monophyly of the clade that contains Isaberrysaura within
yreophora in both datasets. Aer enforcing the constraint, the same search settings as those described above
were used for the constrained search.
e Templeton test42,43 was used to test the signicance of these results. e test was run using a modied
version of the TNT script by Schmidt-Lebuhn (see SupplementaryInformation, C4, original script can be down-
loaded at http://www.anbg.gov.au/cpbr/tools/templetontest.tnt). e Templeton test compares topologies in pairs
in order to ascertain whether they are both signicantly supported by the data or whether one of them can be
rejected. is test has been used in previous dinosaur studies, normally comparing the topologies of one of the
most parsimonious trees with one or more constrained topologies, both topologies being chosen at random from
the results of the normal and constrained tree searches. Due to the high numbers of trees recovered in both the
normal and constrained searches performed in our study, we consider that a comparison of one pair of trees may
not be representative, so we modied the script from Schmidt-Lebuhn (Schmidt-Lebuhn, n.d.) to run for 1000
iterations, each time choosing pairs of trees at random, and recording the results of each Templeton test in a table
that is saved as an output le. e script works in the current version of TNT, and a detailed description of how it
works is included with the script in the supplementaryinformation.
References
1. Molnar, . E. & Cliord, H. T. Gut contents of a small anylosaur. J. Vertebr. Paleontol. 20, 194–196 (2000).
2. Tweet, J. S., Chin, ., Braman, D. . & Murphy, N. L. Probable gut contents within a specimen of Brachylophosaurus canadensis
(Dinosauria: Hadrosauridae) from the Upper Cretaceous Judith iver Formation of Montana. PALAIOS 23, 624–635 (2008).
3. Butler, . J., Barrett, P. M., enric, P. & Penn, M. G. Testing co-evolutionary hypotheses over geological timescales: interactions
between Mesozoic non-avian dinosaurs and cycads. Biol. ev. 84, 73–89 (2009).
4. Mustoe, G. E. Coevolution of cycads and dinosaurs. Cycad Newsl. 30, 6–9 (2007).
5. Norman, D. B. & Barrett, P. M. Ornithischian dinosaurs from the lower cretaceous (Berriasian) of England. Spec. Pap. Palaeontol. 68,
161–189 (2002).
6. Sereno, P. Taxonomy, morphology, masticatory function and phylogeny of heterodontosaurid dinosaurs. Zooeys 226, 1–225 (2012).
7. Pol, D., auhut, O. W. M. & Becerra, M. A Middle Jurassic heterodontosaurid dinosaur from Patagonia and the evolution of
heterodontosaurids. Naturwissenschaen 98, 369–379 (2011).
8. Leanza H. A. Estratigrafía del Paleozoico y Mesozoico anterior a los Movimientos Intramálmicos en la comarca del Cerro Chachil,
Provincia del Neuquén. evista de la Asociación Geológica Argentina 45, 272− 299 (1990).
9. Dietze, V., Hillebrandt, A., iccardi, A. & Schweigert, G. Ammonites and stratigraphy of a Lower Bajocian (Middle Jurassic) section
in Sierra Chacaico (Neuquén Basin, Argentina). Zitteliana A 52, 119–139 (2012).
10. osenfeld, U. Litología y sedimentología de la Formación Lajas (Jurásico Medio) en la parte austral de la Cuenca Neuquina,
Argentina. Acta Geológica Lilloana 15, 105–117 (1978).
11. Spalletti, L. A. Depósitos de tormenta en un frente deltaico. Jurásico medio de la cuenca Neuquina, epública Argentina. ev. Soc.
Geol. España 8, 261–272 (1995).
12. Salgado, L. & Gasparini, Z. El registro más antiguo de dinosauria en la Cuenca Neuquina (Aaleniano, Jurásico Medio). Ameghiniana
41, 505–508 (2004).
13. Boyd, C. A. e cranial anatomy of the neoornithischian dinosaur escelosaurus neglectus. PeerJ 2; doi: 10.7717/peerJ.669 (2014).
14. Sereno, P. C. & Dong, Z. e sull of the basal stegosaur Huayangosaurus taibaii and a cladistic diagnosis of stegosauria. J. Vertebr.
Paleontol. 12, 318–343 (1992).
15. Barrett, P. M., Butler, . J. & noll, F. Small-bodied ornithischian dinosaurs from the Middle Jurassic of Sichuan, China. J. Vertebr.
Paleontol. 25, 823–834 (2005).
16. Godefroit, P. et al. A Jurassic ornithischian dinosaur from Siberia with both feathers and scales. Science 345, 451–455 (2014).
17. Butler, . J., Upchurch, P. & Norman, D. B. e phylogeny of the ornithischian dinosaurs. Journal of Systematic Palaeontology 6, 1–40
(2008).
18. Maidment, S. C. . & Porro, L. B. Homology of the palpebral and origin of supraorbital ossications in ornithischian dinosaurs.
Lethaia 43, 95–111 (2010).
19. Norman, D. B., Witmer, L. M. & Weishampel, D. B. Basal Ornithischia in e Dinosauria: Second Edition (eds Weishampel, D. B.,
Dodson, P. & Osmólsa, H.) Ch. 14, 325–334 (University of California Press, 2004).

www.nature.com/scientificreports/
9
Scientific RepoRts | 7:42778 | DOI: 10.1038/srep42778
20. Coe, M., Dilcher, D., Farlow, J., Jarzen, D. & ussell, D. Dinosaurs and land plants in Origins of angiosperms and their biological
consequences (eds Friis, E., Chaloner, W. & Crane) Ch. 9, 225–258 (Cambridge University Press, 1987).
21. Norstog, . J. & Nicholls, T. J. Biology of the cycads (Cornell University Press, 1997).
22. Barrett, P. M. Prosauropod dinosaurs and iguanas: speculations on the dies of extinct reptiles in Evolution of herbivory in terrestrial
vertebrates: perspectives for m the fossil record (ed. Sues, H.-D.) 42–78 (Cambridge University Press, 2000).
23. Maovicy, P. J., ilbourne, B. M., Sadleir, . W. & Norell, M. A. A new basal ornithopod (Dinosauria, Ornithischia) from the Late
Cretaceous of Mongolia. Journal of Vertebrate Paleontology 31, 626–640 (2011).
24. uiz-Omeñaca, J. I. et al. A new basal ornithopod dinosaur from the Barremian of Galve, Spain. Comptes endus Palevol 11,
435–444 (2012).
25. Barrett, P. M. et al. A palaeoequatorial ornithischian and new constraints on early dinosaur diversication. Proc. . Soc. B 281, doi:
10.1098/rspb.2014.1147 (2014).
26. Baron, M. G., Norman, D. B. & Barrett, P. M. Postcranial anatomy of Lesothosaurus diagnosticus (Dinosauria: Ornithischia) from the
Lower Jurassic of southern Africa: implications for basal ornithischian taxonomy and systematics. Zool. J. Linn. Soc. n/a-n/a,
doi: 10.1111/zoj.12434 (2016).
27. Boyd, C. A. e systematic relationships and biogeographic history of ornithischian dinosaurs. PeerJ 3, e1523 (2015).
28. Archangelsy, S. Megaoras Fósiles, Paleobotánica (Bioestratigrafía) in elatorio del 7° Congreso Geológico Argentino, Geología y
ecursos Naturales del Neuquén (ed. Asociación Geológica Argentina) 187− 193 (Asociación Geológica Argentina, 1978).
29. Quatrocchio, M., García, V., Martínez, M. & Zavala, C. A hypothetic scenario for de Middle Jurassic in the southern part of the
Neuquén Basin, Argentina. Actas del VII International Symposium on Mesozoic Terrestrial Ecosystems, Publicación Especial de la
Asociación Paleontológica Argentina 7, 163− 166 (2001).
30. Morel, E. M., Artabe, A. E., Martínez, L. C. A., Zúñiga, A. & Ganuza, D. G. Megaoras Mesozoicas in elatorio del XVIII Congreso
Geológico Argentino. Geología y ecursos Naturales de la provincia del Neuquén (eds. Leanza, H., Arregui, C., Carbone, O., Danieli, J. C.
& Vallés, J. M.) 573− 578 (Asociación Geológica Argentina, 2011).
31. Volheimer, W., auhut, O. W. M., Quattrocchio, M. E. & Martínez, M. A. Jurassic paleoclimates in Argentina, a review. evista de
la Asociación Geológica Argentina 63, 549–556 (2008).
32. Legarreta, L. & Uliana, M. A. Jurassic-Cretaceous marine oscillations and geometry of bac-arc basin ll, central Argentine Andes
in Sedimentation, Tectonics and Eustasy. Special Publication of the International Association of Sedimentologists (ed. Macdonald, D. J. M.)
12, 429− 450 (International Association of Sedimentologists, 1991).
33. Legarreta, L. & Uliana, M. A. e Jurassic succession in west-central Argentina: stratal patterns, sequences and paleogeographic
evolution. Palaeogrography, Palaeoclimatology, Palaeoecology, 120, 303− 330 (1996).
34. Leanza, H. A. Las principales discordancias del Mesozoico de la Cuenca Neuquina según observaciones de supercie. evista del
Museo Argentino de Ciencias Naturales, n.s. 11, 145− 184 (2009).
35. Volheimer, W. Palinología estratigráca del Jurásico de la Sierra de Chacai Co y adyacencias (Cuenca Neuquina, epública
Argentina). I: Estratigrafía de las formaciones Sierra Chacai Co (Pliensbachiano), Los Molles (Toarciano, Aaleniano), Cura Niyeu
(Bayociano) y Lajas (Caloviano Inferior). Ameghiniana 10, 105− 129 (1973).
36. Gulisano, C. A., Gutiérrez Pleimling, A. . & Digregorio, . E. Esquema estratigráco de la secuencia jurásica del oeste de la
provincia del Neuquén. 9° Congreso Geológico Argentino 1, 236− 259 (1984).
37. McIlroy, D., Flint, S., Howell, J. A. & Timms, N. Sedimentology of the tide-dominated Jurassic Lajas Formation, Neuquén Basin,
Argentina in e Neuquén Basin, Argentina: A case study in sequence stratigraphy and basin dynamics. Special Publication of the
Geological Society of London (eds Veiga, G. D., Spalletti, L. A., Howell, J. A. & Schwarz, E.) 252, 83− 107 (Geological Society of
London, 2005).
38. Arregui, C., Carbone, O. & Martínez, . El Grupo Cuyo (Jurásico Temprano-Medio) en la Cuenca Neuquina. elatorio del 18°
Congreso Geológico Argentino, 77− 89 (2011).
39. Gugliotta, M., Flint, S. S., Hodgson, D. M. & Veiga, G. D. Stratigraphic record of river-dominated crevasse subdeltas with tidal
inuence (Lajas Formation, Argentina). Journal of Sedimentary esearch 85, 265− 284 (2015).
40. Han, F.-L., Barrett, P. M., Butler, . J. & Xu, X. Postcranial anatomy of Jeholosaurus shangyuanensis (Dinosauria, Ornithischia) f rom
the Lower Cretaceous Yixian Formation of China. J. Ver tebr. Paleontol. 32, 1370–1395 (2012).
41. Golobo, P. A., Farris, J. S. & Nixon, . C. TNT, a free program for phylogenetic analysis. Cladistics 24, 774–786 (2008).
42. Templeton, A. . Phylogenetic Inference From estriction Endonuclease Cleavage Site Maps with Particular eference to the
Evolution of Humans and the Apes. Evolution 37, 221–244 (1983).
43. Wilson, J. A. Sauropod dinosaur phylogeny: critique and cladistic analysis. Zoological Journal of the Linnean Society 136, 215–275 (2002).
Acknowledgements
is paper forms part of projects CGL2014- 53548-P subsidized by the Spanish “Ministerio de Economía y
Competitividad”, the European Regional Development Fund, the European Social Fund, the University of
Zaragoza and the Government of Aragón (“Grupos Consolidados”). We are grateful to Isabel Valdivia and Erico
Otilio Berry, who reported the nding to the “Prof. Dr. Juan Olsacher” Museum. We are also grateful to Richard
Butler, Paul M. Barrett, Clint Boyd, and Susannah Maidment for their contributions to substantially improving
the manuscript. Rupert Glasgow edited the text in English. Débora Palledini cooperated in the preparation of the
material, and the Dirección Provincial de Minería de Neuquén provided logistical support for the eldwork. e
Subsecretaría de Cultura de Neuquén granted the eldwork permits.
Author Contributions
L.S., J.I.C., A.C.G., M.M.-A., L.C.A.M., R.A.C. and J.M.G. designed the study, collected data, performed the
comparative and analytical work, and wrote the paper. A.C.G. did the geological work and made the geological
map, and L.C.M. carried out the identication and analysis of the seeds. All authors discussed the results and
commented on the manuscript.
Additional Information
Supplementary information accompanies this paper at http://www.nature.com/srep
Competing nancial interests: e authors declare no competing nancial interests.
How to cite this article: Salgado, L. et al. A new primitive Neornithischian dinosaur from the Jurassic of
Patagonia with gut contents. Sci. Rep. 7, 42778; doi: 10.1038/srep42778 (2017).
Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and
institutional aliations.

www.nature.com/scientificreports/
10
Scientific RepoRts | 7:42778 | DOI: 10.1038/srep42778
is work is licensed under a Creative Commons Attribution 4.0 International License. e images
or other third party material in this article are included in the article’s Creative Commons license,
unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license,
users will need to obtain permission from the license holder to reproduce the material. To view a copy of this
license, visit http://creativecommons.org/licenses/by/4.0/
© e Author(s) 2017