[Paleontology • 2024] Koleken inakayali • A New abelisaurid Dinosaur from the end Cretaceous of Patagonia and Evolutionary Rates among the Ceratosauria

 

Koleken inakayali 

 Pol,  Baiano, Černý, Novas, Cerda & Pittman, 2024

 

DOI: 10.1111/cla.12583

Abstract

Gondwanan dinosaur faunae during the 20 Myr preceding the Cretaceous–Palaeogene (K/Pg) extinction included several lineages that were absent or poorly represented in Laurasian landmasses. Among these, the South American fossil record contains diverse abelisaurids, arguably the most successful groups of carnivorous dinosaurs from Gondwana in the Cretaceous, reaching their highest diversity towards the end of this period. Here we describe Koleken inakayali gen. et sp. n., a new abelisaurid from the La Colonia Formation (Maastrichtian, Upper Cretaceous) of Patagonia. Koleken inakayali is known from several skull bones, an almost complete dorsal series, complete sacrum, several caudal vertebrae, pelvic girdle and almost complete hind limbs. The new abelisaurid shows a unique set of features in the skull and several anatomical differences from Carnotaurus sastrei (the only other abelisaurid known from the La Colonia Formation). Koleken inakayali is retrieved as a brachyrostran abelisaurid, clustered with other South American abelisaurids from the latest Cretaceous (Campanian–Maastrichtian), such as Aucasaurus, Niebla and Carnotaurus. Leveraging our phylogeny estimates, we explore rates of morphological evolution across ceratosaurian lineages, finding them to be particularly high for elaphrosaurine noasaurids and around the base of Abelisauridae, before the Early Cretaceous radiation of the latter clade. The Noasauridae and their sister clade show contrasting patterns of morphological evolution, with noasaurids undergoing an early phase of accelerated evolution of the axial and hind limb skeleton in the Jurassic, and the abelisaurids exhibiting sustained high rates of cranial evolution during the Early Cretaceous. These results provide much needed context for the evolutionary dynamics of ceratosaurian theropods, contributing to broader understanding of macroevolutionary patterns across dinosaurs.

DINOSAURIA Owen, 1842.

THEROPODA Marsh, 1881.

CERATOSAURIA Marsh, 1884.

ABELISAURIDAE Bonaparte and Novas, 1985

BRACHYROSTRA Canale et al., 2009

FURILEUSAURIA Filippi et al., 2016

Koleken gen. n. 

Derivation of name: Adapted from Kóleken, a name in Teushen language spoken by the native population of central Patagonia that means “coming from clay and water”, given the specimen was found in a sedimentary section dominated by claystone representing an estuarine environment.

Koleken inakayali gen. et sp. n.

Derivation of name: Honouring Inakayal, one of the last chiefs of Tehuelches, native people from central Patagonia. He is known for his resistance against Argentina's Conquest of the Desert military campaign, which resulted in the decimation and displacement of native communities from Patagonia. After his capture and eventual death in 1888, Inakayal's skeleton was stored at the La Plata Museum Anthropology collection but in 1994 his skeleton was respectfully restituted in its native place and buried by his people near the town of Tecka, in central Patagonia (Chubut Province, Argentina).

Holotype: MPEF-PV 10826. The specimen includes closely associated (but disarticulated) remains of the skull and atlas, as well as the articulated postcranial skeleton composed of the posteriormost eight dorsal vertebrae, a complete sacrum, eight caudal vertebrae, an almost complete pelvis and hind limbs. Select measurements are provided in Table S1.

Locality and horizon: The specimen was found at the Cerro Bayo Norte area, east of the Sierra de La Colonia, centre north of Chubut Province, Argentina (Fig. 1). Precise geographical provenance is deposited at the MPEF collection. The specimen was found close to the base of the stratigraphic section of the La Colonia Formation that crops out in this region (see Gasparini et al., 2015: Fig. 2). The age of the base of this unit has been recently restricted to the early Maastrichtian (Clyde et al., 2021), constraining the age of the new taxon to the Maastrichtian.

Diagnosis: Koleken inakayali is a brachyrostran abelisaurid different from other theropods in having the following set of autapomorphies (marked with a *): (i) medially smooth paradental plates; (ii) dorsal surface of the nasal with a row of foramina orientated obliquely with respect to the longitudinal skull axis; (iii) *anterior ramus of the postorbital lacking the lateral wall reflected by a dorsoventral height less than half of its anteroposterior length, which makes the orbital surface face ventrally instead ventromedially; (iv) *dorsal surface of the postorbital with a ...

Diego Pol, Mattia Antonio Baiano, David Černý, Fernando E. Novas, Ignacio A. Cerda and Michael Pittman. 2024. A New abelisaurid Dinosaur from the end Cretaceous of Patagonia and Evolutionary Rates among the Ceratosauria. Cladistics. DOI: 10.1111/cla.12583

[Paleontology • 2024] Kiyacursor longipes • The Last Ceratosaur of Asia: A New noasaurid from the Early Cretaceous Great Siberian Refugium

Kiyacursor longipes

  Averianov, Skutschas, Atuchin, Slobodin, Feofanova & Vladimirova, 2024

DOI: 10.1098/rspb.2024.0537 

 facebook.com/AndreyAtuchin

 

Abstract

The noasaurid ceratosaur Kiyacursor longipes gen. et sp. nov. is described based on a fragmentary skeleton including cervical vertebra, pectoral girdle, humerus and hind limbs from the Lower Cretaceous (Aptian) Ilek Formation at Shestakovo 1 locality in Western Siberia, Russia. This is the first ceratosaur from the Early Cretaceous of Asia, extending the stratigraphic range of Ceratosauria by 40 Myr on that continent. Kiyacursor shares unique hind limb proportions with Elaphrosaurus and Limusaurus, suggesting improved cursorial ability. These taxa show an ostrich-like specialization of the pes, with a large third metatarsal and greatly reduced second metatarsal. By contrast, all other fast running non-avian theropod dinosaurs have an arctometatarsalian pes, with the third metatarsal strongly reduced proximally. The new taxon lived in the Early Cretaceous ecosystem containing a number of other Jurassic relics, such as stem salamanders, protosuchian and shartegosuchid crocodyliforms, tritylodontid synapsids and docodontan mammaliaforms.

Keywords: Dinosauria, Theropoda, Ceratosauria, Early Cretaceous, Western Siberia, Russia

Kiyacursor longipes gen. et sp. nov.

 

Alexander O. Averianov, Pavel P. Skutschas, Andrey A. Atuchin, Dmitry A. Slobodin, Olga A. Feofanova and Olga N. Vladimirova. 2024. The Last Ceratosaur of Asia: A New noasaurid from the Early Cretaceous Great Siberian Refugium. Proc. R. Soc. B. 291: 20240537. DOI: 10.1098/rspb.2024.0537

  facebook.com/AndreyAtuchin/posts/7719961694691233

 

[Paleontology • 2020] Tralkasaurus cuyi • A New Abelisaurid (Ceratosauria: Abelisauridae) from the Huincul Formation (Cenomanian-Turonian; Upper Cretaceous) of Río Negro Province, Argentina

Tralkasaurus cuyi 

 Cerroni, Motta, Agnolín, Aranciaga Rolando, Brissón Egli & Novas, 2020

DOI: 10.1016/j.jsames.2019.102445 

twitter.com/CTyS_UNLaM

Highlights: 

• We describe a new species of Abelisauride from the Huincul Formation (Cenomanian-Turonian), Rio Negro province, Patagonia, Argentina.

• Tralkasaurus cuyi nov. gen. et sp. constitutes a new form of medium-sized abelisaurid.

• The phylogenetic analysis resulted in the nesting of Tralkasaurus as a basal abelisaurid.

• The new abelisaurid affords new evidence regarding small to medium-sized abelisaurids from Patagonia.

Abstract

The record of abelisaurids in South America, particularly Argentina is relatively abundant. However, abelisaurid diversity is far from being well-known. Huincul Formation has yielded diverse theropod remains, including the abelisaurids Ilokelesia and Skorpiovenator. The aim of the present contribution is to describe a new abelisaurid coming from the Upper Section of the Huincul Formation (Cretaceous; Cenomanian-Turonian) at the Violante Farm fossil site, Río Negro province, northern Patagonia, Argentina. The new taxon described in this contribution is represented by an incomplete specimen including well-preserved maxilla and dorsal vertebrae, and distorted pelvic girdle and caudal and sacral vertebrae. Its size, much smaller than large abelisaurids as Abelisaurus and Carnotaurus indicates that the new taxon probably occupied a different ecological niche within the carnivoran guild.

Keywords: Abelisauridae, Upper Cretaceous, Río Negro province, Patagonia, Argentina

Systematic paleontology

Theropoda Marsh 1881

Ceratosauria Marsh, 1884

Abelisauroidea Bonaparte, 1991.

Abelisauridae Bonaparte and Novas, 1985.

Tralkasaurus cuyi gen. et sp. nov.

Holotype. MPCA-Pv 815 is represented by associated material including a right maxilla, distorted and incomplete dorsal, sacral and caudal vertebrae, cervical ribs, and pubis (Fig. 1).

Etymology. Tralka, means thunder in Mapudungun language, saurus means lizard in Ancient Greek; cuyi, ...

Conclusions: 

Here we described the new genus and species Tralkasaurus cuyi from Huincul Formation (Cenomanian-Turonian) beds. This new abelisaurid has a relatively small body size, as inferred from available bones. The size of Tralkasaurus contrasts with that of typical abelisaurids such as Abelisaurus and Carnotaurus, indicating that it would occupy a different ecological niche.

Furthermore, Tralkasaurus together with an unnamed abelisaurid from Cenomanian beds described by Canale et al. (2016) increases ...

 M. A. Cerroni, M. J. Motta, F. L. Agnolín, A. M. Aranciaga Rolando, F. Brissón Egli and F. E. Novas. 2020. A New Abelisaurid from the Huincul Formation (Cenomanian-Turonian; Upper Cretaceous) of Río Negro Province, Argentina. Journal of South American Earth Sciences. 98; 102445. DOI: 10.1016/j.jsames.2019.102445

 twitter.com/CTyS_UNLaM/status/1228011186656104448

[Paleontology • 2022] Elemgasem nubilus • A New Brachyrostran Abelisaurid (Ceratosauria: Abelisauridae) from the Portezuelo Formation (Upper Cretaceous) of Patagonia, Argentina

Elemgasem nubilus

  Baiano, Pol, Bellardini, Windholz, Cerda, Garrido & Coria, 2022

DOI: 10.1002/spp2.1462 

  twitter.com/ThePalAss 

Abstract

Abelisaurids are medium–large-sized theropod dinosaurs that were predominant in the carnivorous fauna during the Late Cretaceous of Gondwana. These predators are abundant in the Cretaceous fossil strata of Patagonia, which yield the best record for this group. In the Late Cretaceous, abelisaurids appear in almost all regions of Gondwana and in all stages, except for the Coniacian, in which they are globally unknown. Here we describe a new abelisaurid, Elemgasem nubilus gen. et sp. nov., from the Portezuelo Formation (Turonian–Coniacian), Patagonia, Argentina. The palaeohistology of the appendicular bones of Elemgasem shows that the holotype was a subadult individual, but had achieved sexual maturity. This taxon is based on several axial and appendicular elements, and is diagnosed by the presence of a marked pattern of rugosity on the lateral surface of the fibula and a dorsoventrally deep lateral wall of the calcaneum. Moreover, the posterior caudal vertebrae have a morphology slightly different from any other abelisaurid. Elemgasem nubilus is recovered as an unstable taxon within Brachyrostra, given that it was recovered as sister taxon of Furileusauria or in several positions within this clade. Despite the problematic phylogenetic relationships of Elemgasem nubilus, it is important because it is the first abelisaurid from the Turonian–Coniacian interval and it increases the diversity of this theropod family at a time of marked turnover in the tetrapod fauna of South America, global climate change, and mass extinction events recorded worldwide in the marine realm.

Keywords: Gondwana, Turonian, Coniacian, Elemgasem, Furileusauria, abelisaurid

  Elemgasem nubilus gen. et sp. nov.

  

Mattia A. Baiano, Diego Pol, Flavio Bellardini, Guillermo J. Windholz, Ignacio A. Cerda, Alberto C. Garrido and Rodolfo A. Coria. 2022.  Elemgasem nubilus: A New Brachyrostran Abelisaurid (Theropoda, Ceratosauria) from the Portezuelo Formation (Upper Cretaceous) of Patagonia, Argentina. Papers in Palaeontology. DOI: 10.1002/spp2.1462 

  twitter.com/ThePalAss/status/1566784591133917188

[Paleontology • 2022] First Definitive Record of Abelisauridae (Theropoda: Ceratosauria) from the Cretaceous Bahariya Formation, Bahariya Oasis, Western Desert of Egypt

 Reconstruction of the palaeoecosystem of the Upper Cretaceous (Cenomanian) Bahariya Formation of the Bahariya Oasis, Western Desert of Egypt, showing diversity of large-bodied theropod dinosaurs.

in Salem, Lamanna, O'Connor, ... et Sallam, 2022. 

 DOI: 10.1098/rsos.220106

 AUCEgypt.edu 

Artwork by Andrew McAfee, Carnegie Museum of Natural History.

Abstract

Numerous non-avian theropod dinosaur fossils have been reported from the Upper Cretaceous (Cenomanian) Bahariya Formation, Bahariya Oasis, Western Desert of Egypt, but unambiguous materials of Abelisauridae have yet to be documented. Here we report Mansoura University Vertebrate Paleontology Center (MUVP) specimen 477, an isolated, well-preserved tenth cervical vertebra of a medium-sized abelisaurid from the Bahariya Formation. The new vertebra shows affinities with those of other Upper Cretaceous abelisaurids from Madagascar and South America, such as Majungasaurus crenatissimus, Carnotaurus sastrei, Viavenator exxoni and a generically indeterminate Patagonian specimen (Museo Padre Molina specimen 99). Phylogenetic analysis recovers the Bahariya form within Abelisauridae, either in a polytomy of all included abelisaurids (strict consensus tree) or as an early branching member of the otherwise South American clade Brachyrostra (50% majority rule consensus tree). MUVP 477, therefore, represents the first confirmed abelisaurid fossil from the Bahariya Formation and the oldest definitive record of the clade from Egypt and northeastern Africa more generally. The new vertebra demonstrates the wide geographical distribution of Abelisauridae across North Africa during the middle Cretaceous and augments the already extraordinarily diverse large-bodied theropod assemblage of the Bahariya Formation, a record that also includes representatives of Spinosauridae, Carcharodontosauridae and Bahariasauridae.

Keywords: Abelisauridae, Egypt, Africa, Cretaceous, Bahariya Formation

Tenth cervical vertebra of Abelisauridae indet. (MUVP 477)
in cranial (a), caudal (b), left lateral (c), right dorsolateral (d), ventral (e) and dorsal (f) views.

 Reconstruction of the palaeoecosystem of the Upper Cretaceous (Cenomanian) Bahariya Formation of the Bahariya Oasis, Western Desert of Egypt, showing diversity of large-bodied theropod dinosaurs.
In the foreground, the unidentified abelisaurid described herein (right) confronts the spinosaurid Spinosaurus aegyptiacus (left centre, with dipnoan (lungfish) Retodus tuberculatus in jaws) and the carcharodontosaurid Carcharodontosaurus saharicus (right centre) while two individuals of the stomatosuchid crocodyliform Stomatosuchus inermis (left) look on. In the background, a herd of the titanosaurian sauropod Paralititan stromeri (left) warily regards these theropods and two individuals of the bahariasaurid Bahariasaurus ingens (far right) while a small flock of an undescribed pterosaur soars above. The vegetation is dominated by the mangrove-like tree fern Weichselia reticulata.

Artwork by Andrew McAfee, Carnegie Museum of Natural History.

Conclusion: 

The cervical vertebra (MUVP 477) described herein represents the first confirmed fossil of Abelisauridae from the Bahariya Formation, establishing it as the oldest definitive record of this theropod clade from Egypt and northeastern Africa more generally. The new vertebra demonstrates the wide geographical distribution of abelisaurids across North Africa during the middle Cretaceous and augments the already extraordinarily diverse large-bodied non-avian theropod record of the Bahariya Formation, a unit that also preserves representatives of Spinosauridae, Carcharodontosauridae and Bahariasauridae. This abelisaurid/spinosaurid/carcharodontosaurid/bahariasaurid faunal assemblage appears to have extended across most or all of northern Africa during the Cenomanian, suggesting that the Trans-Saharan Seaway did not represent a significant barrier to large-bodied theropod dispersal at this time. The Bahariya Formation holds unrealized potential to improve understanding of this northern African Cenomanian fauna due to the relative commonality of phylogenetically informative associated partial skeletons in this stratigraphic unit.

 

Belal S. Salem, Matthew C. Lamanna, Patrick M. O'Connor, Gamal M. El-Qot, Fatma Shaker, Wael A. Thabet, Sanaa El-Sayed and Hesham M. Sallam. 2022. First Definitive Record of Abelisauridae (Theropoda: Ceratosauria) from the Cretaceous Bahariya Formation, Bahariya Oasis, Western Desert of Egypt. R. Soc. open sci. 9220106. DOI: 10.1098/rsos.220106 

Hesham Sallam Leads Egyptian Team’s Discovery of Bizarre Meat-Eating Dinosaur in Egypt’s Bahariya Oasis 

AUCEgypt.edu/news/hesham-sallam-leads-egyptian-team%E2%80%99s-discovery-bizarre-meat-eating-dinosaur-egypt%E2%80%99s-bahariya

[Paleontology • 2022] Guemesia ochoai • First Definitive Abelisaurid Theropod (Theropoda: Abelisauridae) from the Late Cretaceous of Northwestern Argentina

Guemesia ochoai  

Agnolín, Cerroni, Scanferla, Goswami, Paulina-Carabajal, Halliday, Cuff & Reuil, 2022

DOI: 10.1080/02724634.2021.2002348 

twitter.com/mendolaspis   twitter.com/Ch_Hendrickx

Carnotaurus sastrei Bonaparte, 1985 

 Illustration: Fred Wierum wikimedia.org

 

ABSTRACT

The fossil record of abelisaurid theropods in South America is mostly limited to Brazil and Argentina. In Argentina, abelisaurids are generally known from Patagonia, where their record is relatively abundant and includes well-known and complete specimens. However, for North-western Argentina, abelisaurids are represented by incomplete and isolated bones and teeth that remain largely unpublished. The aim of this contribution is to report a nearly complete abelisaurid braincase from the Late Cretaceous Los Blanquitos Formation (Campanian), Amblayo Valley, Salta province, Argentina. The specimen shows plesiomorphic features for abelisaurids, including a thin skull roof, absence of skull projections like horns or bulges, and low and narrow parietal eminence that lie at the same level as the sagittal crest. Furthermore, the specimen possesses some autapomorphies that support its status as a new taxon and its small size allows it to be assigned as one of the smallest abelisaurids recorded up to date. The finding of this specimen constitutes the first unequivocal occurrence of an abelisaurid in Northwestern Argentina and brings new evidence concerning the geographic distribution of the clade during Late Cretaceous times in South America.

Federico L. Agnolín, Mauricio A. Cerroni, Agustín Scanferla, Anjali Goswami, Ariana Paulina-Carabajal, Thomas Halliday, Andrew R. Cuff and Santiago Reuil. 2022.  First Definitive Abelisaurid Theropod from the Late Cretaceous of Northwestern Argentina. Journal of Vertebrate Paleontology.  e2002348. DOI: 10.1080/02724634.2021.2002348

 twitter.com/mendolaspis/status/1493740256935432195

 twitter.com/Ch_Hendrickx/status/1492158674843967493

 nhm.ac.uk/discover/news/2022/february/new-armless-abelisaur-dinosaur-species-discovered-argentina.html

 commons.wikimedia.org/wiki/File:Carnotaurus_2017.png

      

[Paleontology • 2021] Berthasaura leopoldinae • The First edentulous Ceratosaur (Ceratosauria: Abelisauroidea: Noasauridae) from South America

 

Berthasaura leopoldinae 

de Souza, Soares, Weinschütz, Wilner, Lopes, de Araújo & Kellner, 2021

DOI: 10.1038/s41598-021-01312-4

Abstract

The recognition of ontogenetic edentulism in the Jurassic noasaurid Limusaurus inextricabilis shed new light on the dietary diversity within Ceratosauria, a stem lineage of non-avian theropod dinosaurs known for peculiar craniomandibular adaptations. Until now, edentulism in Ceratosauria was exclusive to adult individuals of Limusaurus. Here, an exceptionally complete skeleton of a new toothless ceratosaur, Berthasaura leopoldinae gen. et sp. nov., is described from the Cretaceous aeolian sandstones of the Bauru Basin, Southern Brazil. The specimen resembles adult individuals of Limusaurus by the absence of teeth but based on the unfused condition of several elements (e.g., skull, vertebral column) it clearly represents an ontogenetically immature individual, indicating that it might never have had teeth. The phylogenetic analysis performed here has nested Berthasaura leopoldinae as an early-divergent Noasauridae, not closely related to Limusaurus. It represents the most complete non-avian theropod from the Brazilian Cretaceous and preserves the most complete noasaurid axial series known so far. Moreover, the new taxon exhibits many novel osteological features, uncommon in non-avian theropods, and unprecedented even among South American ceratosaurs. These include not only toothless jaws but also a premaxilla with cutting occlusal edge, and a slightly downturned rostral tip. This indicate that B. leopoldinae unlikely had the same diet as other ceratosaurs, most being regarded as carnivorous. As the ontogenetically more mature specimens of Limusaurus, Berthasaura might have been herbivorous or at least omnivorous, corroborating with an early evolutionary divergence of noasaurids from the ceratosaurian bauplan by disparate feeding modes.

Berthasaura leopoldinae gen. et sp. nov., holotype (MN 7821-V), nearly complete skeleton.
 (a) Photograph. (b) Respective line drawing.

Interpretative line drawing of Berthasaura leopoldinae gen. et sp. nov., holotype (MN 7821-V), and photographs.
(a) Line drawing reconstruction

  

Berthasaura leopoldinae gen. et sp. nov. holotype (MN 7821-V), interpretative line drawing of the skull and photographs of cranial bones.
(a) Interpretative reconstruction of the skull.

Systematic paleontology

Dinosauria Owen, 1842

Theropoda Marsh, 1881

Abelisauroidea (Bonaparte and Novas, 1985) sensu Wilson et al.13

Noasauridae Bonaparte & Powell, 1980 sensu Wilson et al.13

Berthasaura leopoldinae gen. et sp. nov.

Holotype: MN 7821-V comprises a nearly complete disarticulated skeleton, including a partial skull and lower jaw

Horizon and locality: Cemitério dos Pterossauros Quarry, Goio Erê Formation, Early Cretaceous (Aptian-Albian), Caiuá Group, Bauru Basin. The fossils were collected in layers that crop out in a rural road at Cruzeiro do Oeste Municipality, Paraná State, Southern Brazil.

Diagnosis: Noasaurid ceratosaur with the following combination of characters that distinguishes it from other members of the clade (autapomorphies are marked with an asterisk): edentulous rostrum (premaxilla, maxilla and dentary); lamellae on the medial surface of the premaxilla*; short dentaries with the length rostral to the mandibular fenestra about 1.5 times the height of the dentary*; protuberance projecting from the caudoventral end of the premaxillary buccal rim*; non-bifurcated rostral end of splenial*; postzygodiapophyseal lamina in mid-cervical vertebrae divided in two parts and reduced to low ridges; maximal length of metacarpus less than 15% of the length of humerus; iliac blade mediolaterally flattened; medial brevis shelf strongly reduced*; deep notch on the caudal margin of the ischial process producing an eminent and caudally-oriented prong*; rounded medial femoral epicondyle.

Etymology: The generic name honors the researcher Bertha Maria Júlia Lutz (1894–1976) for her scientific contribution and social activity particularly regarding woman rights in Brazil, combined with saura, feminine of saurus from the Greek for lizard. The specific epithet leopoldinae honors the first Brazilian empress, Maria Leopoldina (1797–1826), for her fundamental role in the independency of Brazil that next year (2022) will complete two centuries; and the samba school Imperatriz Leopoldinense, that in the 2018 carnival developed the theme "A Royal Night at the Museu Nacional" (Uma noite real no Museu Nacional) in commemoration of the bicentenary of the museum. This was before the large fire of September 2018.

 

Life reconstruction of Berthasaura leopoldinae gen. et sp. nov. in the paleoenvironment represented by the “Cemitério dos Pterossauros” Quarry.

Geovane Alves de Souza, Marina Bento Soares, Luiz Carlos Weinschütz, Everton Wilner, Ricardo Tadeu Lopes, Olga Maria Oliveira de Araújo and Alexander Wilhelm Armin Kellner. 2021. The First edentulous Ceratosaur from South America. Scientific Reports. 11, 22281. DOI: 10.1038/s41598-021-01312-4

 

[Paleontology • 2021] The Scaly Skin of the abelisaurid Carnotaurus sastrei (Theropoda: Ceratosauria) from the Upper Cretaceous of Patagonia

Carnotaurus sastrei  Bonaparte, 1985

in Hendrickx & Bell, 2021.

DOI: 10.1016/j.cretres.2021.104994 

Illustration: J. Baardse twitter.com/LittleBaardo 

Abstract

The integument of the theropod dinosaur Carnotaurus sastrei from the Upper Cretaceous of Argentina is here described in detail for the first time. The scaly skin of this abelisaurid is the most completely preserved of any theropod and the only example of this form of integument known outside of Tetanurae (excluding footprints). The skin is preserved in the shoulder, thoracic, tail and, possibly, neck regions and consists of medium to large (20–65 mm in diameter) conical feature scales surrounded by a network of low and small (<14 mm) non-imbricating basement scales separated by narrow interstitial tissue. Contrary to previous interpretations, the feature scales are randomly distributed and neither form discrete rows nor show progressive variations in their size along parts of the body. They also show little difference in morphology along the body, although their apices are variously positioned in different body parts. Conversely, the basement scales vary from small and elongated, large and polygonal, and circular-to-lenticular in the thoracic, scapular, and tail regions, respectively. Given the presumed active lifestyle of Carnotaurus and the necessity of shedding excess heat, particularly at large body sizes (>1000 kg), we speculate that the skin may have played a vital role in thermoregulation; a role consistent with integument function in extant mammals and reptiles.

 

Keywords: Integument, Scales, Abelisauridae, Non-avian Theropoda, Skin

 Christophe Hendrickx and Phil R. Bell. 2021. The Scaly Skin of the abelisaurid Carnotaurus sastrei (Theropoda: Ceratosauria) from the Upper Cretaceous of Patagonia. Cretaceous Research. 128, 104994. DOI: 10.1016/j.cretres.2021.104994 

 twitter.com/LittleBaardo/status/1436388923614187524

twitter.com/TylerGreenfieId/status/1426322079062794240

[Paleontology • 2021] Llukalkan aliocranianus • A New Furileusaurian Abelisaurid from La Invernada (Upper Cretaceous, Santonian, Bajo De La Carpa Formation), Northern Patagonia, Argentina

Llukalkan aliocranianus 

Gianechini, Méndez, Filippi, Paulina-Carabaja, Juárez-Valieri & Garrido, 2021

DOI: 10.1080/02724634.2020.1877151 

ABSTRACT

Abelisaurids are among the most abundant and diverse Patagonian Late Cretaceous theropods. Here, we present a new furileusaurian abelisaurid, Llukalkan aliocranianus gen. et sp. nov., represented by cranial remains from the Bajo de la Carpa Formation (Santonian) at La Invernada fossil area, northwestern Patagonia. Features characterizing this taxon include a possible caudal tympanic recess posterior to the columellar recess, a T-shaped lacrimal with jugal ramus lacking a suborbital process, and large foramina for caudal middle cerebral veins widely separated from the median supraoccipital crest. In addition to this, a bulge on the anteromedial border of the supratemporal fossa, tall and posteriorly projected paroccipital processes, basal tubera interconnected distally, a triangular basisphenoid recess, and a single foramen for the sphenoidal artery on the basisphenoid, differentiate Llukalkan from Viavenator exxoni. The latter is the other furileusaurian taxon from the same area and stratigraphic unit. Although the holotype of Llukalkan probably corresponds to a sub-adult—as the lacrimal morphology suggests— the possibility that it represents a juvenile of V. exxoni is discarded based mainly on the presence of a caudal tympanic recess (which is absent in V. exxoni). The probable coexistence of two abelisaurid taxa demonstrates that the abelisaurids were one of the most important—and likely the main—predator component of the ecosystems, not only in this area, but also in all of Patagonia, during the Late Cretaceous.

FIGURE 17. Reconstruction of the complete skull and mandible of Llukalkan aliocranianus, from the Late Cretaceous of Neuquén Province, Argentina, in left lateral view.
The preserved bones are located in their supposed natural positions, whereas non-preserved parts and bones are in gray. The prearticular bone has a medial location, laterally covered by the angular and surangular. The maxilla, jugal and quadrate correspond to the right side, although they were mirrored to accommodate with the image. Scale bar equals 5 cm. For abbreviations in the figure, see text.

FIGURE 1. Provenance of the holotype of Llukalkan aliocranianus (MAU-Pv-LI-581).
 A, map showing the location of La Invernada fossil area; B, photograph of the materials in situ in the field; C, photograph showing the aspect of the outcrops of the Bajo de la Carpa Formation at La Invernada fossil area (indicated with the arrow).

SYSTEMATIC PALEONTOLOGY

THEROPODA Marsh, 1881

CERATOSAURIA Marsh, 1884

ABELISAURIDAE Bonaparte and Novas, 1985

BRACHYROSTRA Canale, Scanferla, Agnolin and Novas, 2009

FURILEUSAURIA Filippi, Méndez, Juárez Valieri and Garrido, 2016

Llukalkan aliocranianus.

Illustration: Jorge Blanco.

LLUKALKAN ALIOCRANIANUS gen. et sp. nov.

 Etymology— Llukalkan, means “one who scares or causes fear” in Mapudungun; aliocranianus means “different skull” in Latin.

Federico A. Gianechini, Ariel H. Méndez, Leonardo S. Filippi, Ariana Paulina-Carabaja, Rubén D. Juárez-Valieri and Alberto C. Garrido. 2021. A New Furileusaurian Abelisaurid from La Invernada (Upper Cretaceous, Santonian, Bajo De La Carpa Formation), Northern Patagonia, Argentina. Journal of Vertebrate Paleontology. e1877151.  DOI: 10.1080/02724634.2020.1877151 

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