[Paleontology • 2025] Joaquinraptor casali • Latest Cretaceous megaraptorid theropod Dinosaur sheds light on megaraptoran evolution and palaeobiology

 

Joaquinraptor casali 

Ibiricu, Lamanna, Alvarez, Cerda, Caglianone, Cardozo, Luna & Martínez, 2025 

 DOI: doi.org/10.1038/s41467-025-63793-5 

Artwork by  Andrew McAfee

Abstract

Recent fossil discoveries have cast considerable light on the palaeobiology of Megaraptora, a group of large-clawed carnivorous theropod dinosaurs known from Cretaceous deposits in Asia, Australia, and especially South America. Nevertheless, many important aspects of megaraptoran morphology and evolution remain poorly understood, due in large part to the fragmentary nature of most fossils of these theropods and the scarcity of anatomically overlapping skeletal elements among the known taxa. Here we report a previously unknown megaraptoran genus and species represented by a partially articulated partial skeleton recovered from an uppermost Cretaceous stratum of the Lago Colhué Huapi Formation of south-central Chubut Province in central Patagonia, Argentina. Pertaining to the derived megaraptoran subclade Megaraptoridae, the taxon is among the most completely represented and latest-surviving megaraptorans. Its stratigraphic occurrence indicates that these dinosaurs likely persisted to the Cretaceous/Palaeogene boundary; moreover, the preservation of a crocodyliform humerus between the dentaries of the new theropod may provide information on megaraptoran dietary preferences and feeding strategies. Megaraptorids appear to have been the apex predators in central and southern Patagonian palaeoecosystems approaching the end of the Cretaceous, in contrast to more northerly areas of South America where these niches were occupied by other non-avian theropod groups.

 Osteology of Joaquinraptor casali gen. et sp. nov.
a Skeletal reconstruction of Joaquinraptor in left lateral view with preserved elements in blue (some reversed from right side) (modified and updated from Lamanna et al.7 [these authors’ Fig. 1e], which was in turn modified by A. McAfee from an original illustration by T.K. Robinson). Right maxilla in lateral (b) and medial (c) views. Skull roof, braincase, and atlantal intercentrum in dorsal (d) and ventral (e) views. f Probable right postorbital in lateral view. g Right quadrate in anterior view. Right and left dentaries in lateral and medial views (right dentary in lateral view and left dentary in medial view in h; opposite in i). j Two articulated middle or posterior caudal vertebrae in right lateral view. k Dorsal rib in anterior view. l Anterior haemal arch in anterior view. m Left scapulocoracoid in lateral view. Left humerus in anterolateral (n), lateral (o), and medial (p) views. Left radius in anterior (q) and lateral (r) views. Left ulna in lateral (s) and posterior (t) views. u Right manual ungual II (=manual phalanx II-3) in lateral view. Left femur in anterior (v) and posterior (w) views. x Distal right tibia in anterior view. y Right pedal ungual III (=pedal phalanx III-4) in medial view. Dashed lines indicate missing areas of scapulocoracoid and femur.

Systematic palaeontology

Saurischia Seeley, 1887 

Theropoda Marsh, 1881 

Tetanurae Gauthier, 1986 

Megaraptora Benson, Carrano, and Brusatte, 2010 

Megaraptoridae Novas, Agnolín, Ezcurra, Porfiri, and Canale, 2013 

Joaquinraptor casali gen. et sp. nov.

Etymology: Joaquín, in tribute to the son of the first author (L.M.I.) and the informal name given to the locality when the skeleton of the taxon was discovered (Valle Joaquín); Latin, raptor, thief. Specific epithet casali in recognition of Dr. Gabriel Andrés Casal for his many contributions to knowledge of the Cretaceous palaeontology and geology of central Patagonia (including the formal recognition and naming of the formation from which this megaraptorid was recovered).

Joaquinraptor casali with an ancient crocodile relative's front leg in its mouth.

Artwork by  Andrew McAfee

 

Lucio M. Ibiricu, Matthew C. Lamanna, Bruno N. Alvarez, Ignacio A. Cerda, Julieta L. Caglianone, Noelia V. Cardozo, Marcelo Luna and Rubén D. Martínez. 2025. Latest Cretaceous megaraptorid theropod Dinosaur sheds light on megaraptoran evolution and palaeobiology. Nature Communications. 16: 8298. DOI: doi.org/10.1038/s41467-025-63793-5 [23 September 2025]

[Paleontology • 2025] Rise of the King: Gondwanan Origins and Evolution of Megaraptoran Dinosaurs

Gondwanan Origins and Evolution of Megaraptoran Dinosaurs

in Morrison, Scherer, O’Callaghan, Layton, Boisvert, Rolando, Durrant, Salas, Allain et Gascoigne, 2025. 

DOI: doi.org/10.1098/rsos.242238 

 

Abstract

Late Cretaceous Earth was dominated by theropods such as tyrannosauroids and megaraptorans; however, it is unclear how these clades diversified and grew to massive proportions. This study aimed to conduct a biogeographical analysis and test climate as a potential mechanism for the increase in size. We used published phylogenetic matrices with the R package BioGeoBears to test different biogeographical hypotheses for both clades. We mapped body mass (BM) and body length against known climate data to test this potential hypothesis. Continental-scale variance did not drive tyrannosauroid biogeography and instead widespread ancestral populations, sympatric speciation and localized extinctions throughout these clades constricted geographic range. Both patterns were supported by statistical analyses. This biogeographical model also indicates the ancestor of the clade Tarbosaurus and Tyrannosaurus was present in both Asia and Laramidia, and therefore the ancestor of Tyrannosaurus came from Asia. Statistical data illustrated no correlation between Mean Annual Temperature (MAT) and BM but potential climatic shifts may be associated with gigantism in derived megaraptorids and eutyrannosaurians. This biogeographical model implies megaraptorans may have had a cosmopolitan distribution prior to the splitting of Laurasia and Gondwana. Also, gigantism in these clades may be associated with climatic shifts in the Late Cretaceous.

Keywords: Biogeography, Late Cretaceous, Megaraptora, Tyrannosauroidea

 

The end Cretaceous Northern Hemisphere fauna was dominated by Tyrannosaurids (such as Tyrannosaurus rex), hadrosaurs and ceratopsian ornithischian dinosaurs.

Artwork by Pedro Salas and Sergey Krasovskiy.

Potential dispersal routes for megaraptorans during the Middle Jurassic–Early Cretaceous (approx. 143 Ma). ...

Cassius Morrison, Charlie Roger Scherer, Ezekiel V. O’Callaghan, Collin Layton, Colin Boisvert, Mauro Aranciaga Rolando, Leroy Durrant, Pedro Salas, Steven J. R. Allain and Samuel J. L. Gascoigne. 2025. Rise of the King: Gondwanan Origins and Evolution of Megaraptoran Dinosaurs. R. Soc. Open Sci. 12: 242238. DOI: doi.org/10.1098/rsos.242238  [07 May 2025] 

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[Paleontology • 2025] Evolutionary and Paleobiogeographic Implications of New carcharodontosaurian, megaraptorid, and unenlagiine Theropod Remains from the upper Lower Cretaceous of Victoria, southeast Australia

 

Cretaceous Australia Landscape
 

in Kotevski, Duncan, Ziegler, Bevitt, Vickers-Rich, Rich, Evans & Poropat, 2025. 

DOI: doi.org/10.1080/02724634.2024.2441903  

artwork by Jonathan Metzger

ABSTRACT

The Early Cretaceous non-avian theropod body fossil record of Victoria, Australia dominantly comprises isolated dental and postcranial remains. Numerous specimens have been collected from both the upper Strzelecki Group (upper Barremian–lower Aptian) and Eumeralla Formation (upper Aptian–lower Albian), yet theropod diversity in each unit remains poorly resolved. In both deposits, specimens pertaining to Megaraptoridae—a clade seemingly endemic to South America and Australia in the Cretaceous—are most frequently encountered. However, evidence of other typically common Gondwanan theropod groups, including Abelisauridae and Carcharodontosauria, has remained unknown. Herein, we describe five new theropod specimens: three tibiae, and two articulated caudal vertebrae with haemal arches, from the upper Strzelecki Group; and a single tibia from the Eumeralla Formation. Two of these tibiae—one each from the upper Strzelecki Group and the Eumeralla Formation—provide the first evidence for Carcharodontosauria in Australia. Two megaraptorid specimens from the upper Strzelecki Group—a tibia, and two caudal vertebrae with haemal arches—demonstrate that this clade had achieved large body size at the time of its first appearance in the fossil record. A tibia from the upper Strzelecki Group is interpreted to represent the Gondwanan dromaeosaur clade Unenlagiinae. Collectively, the new theropod remains described herein strengthen the evidence for mid-Cretaceous faunal interchange between Australia and South America across Antarctica, and highlight the presence of carcharodontosaurians and unenlagiines at high latitudes in the late Early Cretaceous.

Carcharodontosauria indet. right tibia (NMV P221042)
from the Eumeralla Formation of Victoria, Australia.  

Cretaceous Australia Landscape.

artwork by Jonathan Metzger, Museums Victoria

Jake Kotevski, Ruairidh J. Duncan, Tim Ziegler, Joseph J. Bevitt, Patricia Vickers-Rich, Thomas H. Rich, Alistair R. Evans and Stephen F. Poropat. 2025. Evolutionary and Paleobiogeographic Implications of New carcharodontosaurian, megaraptorid, and unenlagiine Theropod Remains from the upper Lower Cretaceous of Victoria, southeast Australia. Journal of Vertebrate Paleontology. e2441903. DOI: doi.org/10.1080/02724634.2024.2441903  

[Paleontology • 2023] A megaraptorid (Theropoda: Megaraptora) Frontal from the upper Strzelecki Group (Lower Cretaceous) of Victoria, Australia

in Kotevski, Duncan, Pentland, Rule, Vickers-Rich, ... et Poropat, 2023.

DOI: 10.1016/j.cretres.2023.105769 

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Highlights: 

• First non-mandibular skull element reported for an Australian non-avian theropod.

• Geologically oldest megaraptorid frontal element worldwide.

• Megaraptorid and non-megaraptorid megaraptorans present in upper Strzelecki Group.

Abstract

Cretaceous (non-avian) theropod dinosaurs from Australia are poorly understood, primarily because almost all specimens described thus far comprise isolated postcranial elements. In Australia, only three non-dental cranial elements pertaining to Theropoda have been reported: the left and right dentaries of Australovenator wintonensis from the Winton Formation (Cenomanian–lowermost Turonian) of Queensland, and an isolated surangular from the Eumeralla Formation (lower Albian) of Victoria. Herein, we report the first evidence of non-mandibular cranial material of a non-avian theropod from Australia: a left frontal and fused parietal fragment from the Lower Cretaceous (lower Aptian) upper Strzelecki Group of Victoria. The specimen shares several synapomorphies with the frontals assigned to Megaraptoridae, including an anteroposteriorly elongate postorbital articulation and a truncated nasal articular surface. Accordingly, we regard this frontal as Megaraptoridae gen. et sp. indet. We performed both parsimony-based and Bayesian-based phylogenetic analyses to support our assignment, and both analyses support a placement within Megaraptoridae. However, this specimen appears to possess plesiomorphic characters relative to other megaraptorid frontals, lacking dorsoventrally high walls of bone that emarginate the nasal and prefrontal articular surfaces. The plesiomorphies of this specimen have implications for the evolution of the megaraptoran skull roof, suggesting the acquisition of specialised adaptations for longirostry over time. This specimen improves the limited record of Cretaceous Australian theropod cranial remains, and provides limited support for the hypothesis that Megaraptoridae might have originated in Australia.

 

Keywords: Gondwana, Australia, Dinosauria, Theropoda, Cretaceous, Megaraptoridae

THEROPODA Marsh, 1881.

TETANURAE Gauthier, 1986.

COELUROSAURIA von Huene, 1914.

MEGARAPTORA Benson et al. 2010.

MEGARAPTORIDAE Novas et al. 2013.

Megaraptoridae gen. et sp. indet.

 Referred material: NMV P229038: An isolated, almost complete left frontal, fused to a fragment of the left parietal (Fig. 3).

Graphical abstract depicting major research findings of this report.
Clockwise from top: Geological scale indicating ages of known megaraptoran frontals; Locality map of the upper Strzelecki Group portraying localities yielding Megaraptora and Megaraptoridae fossils (map data cited in Fig. 1);
Life reconstruction of Victorian megaraptorid with approximate life position of NMV P229038 shown in silhouette and in dorsal view (illustration by Ruairidh J. Duncan);
Map of southern hemisphere with modern geographic borders showing approximate location of constituent Gondwanan continents and fossil locality at ∼110Ma.

Southern hemisphere map derived and adapted from Rich et al. (2002). 

Chronostratigraphic data derived from Cohen et al. (2013; updated).

 

Jake Kotevski, Ruairidh J. Duncan, Adele H. Pentland, James P. Rule, Patricia Vickers-Rich, Thomas H. Rich, Erich M.G. Fitzgerald, Alistair R. Evans and Stephen F. Poropat. 2023. A megaraptorid (Dinosauria: Theropoda) Frontal from the upper Strzelecki Group (Lower Cretaceous) of Victoria, Australia. Cretaceous Research. In Press, 105769. DOI: 10.1016/j.cretres.2023.105769

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[Paleontology • 2023] An Unusual Metatarsal of Theropod Dinosaur from the lower Cretaceous of Thailand: the First detailed Study of Paleopathology in Megaraptora

Phuwiangvenator yaemniyomi  Samathi, Chanthasit & Sander, 2019

in Samathi, Weluwanarak, Duanyai, Kaikaew & Suteethorn, 2023.

 DOI: 10.1080/08912963.2023.2166833

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ABSTRACT

A pathological metatarsal of the early-branching megaraptoran Phuwiangvenator yaemniyomi from the Lower Cretaceous of Thailand is here studied. It was CT-scanned and compared with pathology in other dinosaurs and living animals. The result shows that the palaeopathology in Phuwiangvenator was a traumatic fracture, specifically a greenstick fracture, based on the incomplete breakage of the bone, which occurred only on one side and twisted or distorted in the opposite direction to the force that caused the pathology. The cause of the fracture was possibly by accidentally hitting or kicking hard material, fighting, or falling to the ground. Phuwiangvenator was probably an adolescent when it was injured and survived the incident. This is the second report of a greenstick fracture in Theropoda after Akansaurus fridayii; the first detailed analysis of palaeopathology in Megaraptora; and the first record and detailed description of palaeopathology in non-avian theropods in Southeast Asia.

KEYWORDS: Theropoda, megaraptora, Thailand, palaeopathology, fracture, metatarsal

 

Adun Samathi, Jakkrapat Weluwanarak, Punyawee Duanyai, Siripat Kaikaew and Suravech Suteethorn. 2023. An Unusual Metatarsal of Theropod Dinosaur from the lower Cretaceous of Thailand: the First detailed Study of Paleopathology in Megaraptora. Historical Biology: An International Journal of Paleobiology. DOI: 10.1080/08912963.2023.2166833

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[Paleontology • 2022] Maip macrothorax • A large Megaraptoridae (Theropoda: Coelurosauria) from Upper Cretaceous (Maastrichtian) of Patagonia, Argentina

Maip macrothorax

 Aranciaga Rolando, Motta, Agnolín, Manabe, Tsuihiji & Novas, 2022

DOI: 10.1038/s41598-022-09272-z

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Abstract

Megaraptora is a theropod clade known from former Gondwana landmasses and Asia. Most members of the clade are known from the Early to Late Cretaceous (Barremian–Santonian), with Maastrichtian megaraptorans known only from isolated and poorly informative remains. The aim of the present contribution is to describe a partial skeleton of a megaraptorid from Maastrichtian beds in Santa Cruz Province, Argentina. This new specimen is the most informative megaraptoran known from Maastrichtian age, and is herein described as a new taxon. Phylogenetic analysis nested the new taxon together with other South American megaraptorans in a monophyletic clade, whereas Australian and Asian members constitute successive stem groups. South American forms differ from more basal megaraptorans in several anatomical features and in being much larger and more robustly built.

SYSTEMATIC PALAEONTOLOGY

Theropoda Marsh, 1881

Tetanurae Gauthier, 1986

Coelurosauria von Huene, 1920

Megaraptora Benson et al., 2010

Megaraptoridae Novas et al., 2013

(A), silhouette of Maip macrothorax showing the preserved bones in white. (B), reconstruction of the thoracic cavity of Maip at level of D6. (C), interpretative drawing of the excavation of Maip showing the original disposition of the bones.

Abbreviations: a, axis; c, coracoid; ind, indeterminate bone; g, gastralia; r, rib; v, vertebrae.

Maip macrothorax gen. et sp. nov.

 

Derivation of name. Maip is an evil entity from the Aonikenk mythology that represents “the shadow of the death” which “kills with cold wind”, and roams in the Andes mountains. The specific name, macro, derives from the Latin “big” and “thorax” refers to its wide thoracic cavity (which has, approximately, more than 1.20 m width).

 

Locality. Megaraptorid Site (Locality 3; see Novas et al.3), La Anita Farm, 30 km West from El Calafate city, Santa Cruz province, Argentina. Chorrillo Formation (Maastrichtian;3,37,38).

Diagnosis. Megaraptorid theropod diagnosable on the basis of the following combination of characters (autapomorphies marked by an asterisk): 1) mid-dorsal vertebrae with articular surface of parapophyses saddle-shaped (absent in Aerosteon and Murusraptor)*; 2) mid-caudal vertebrae with an accessory posterior centrodiapophyseal lamina that subdivides the postzygapophyseal-centrodiapophyseal fossa in two pneumatic fossae (absent in Aoniraptor, Aerosteon, Megaraptor, and Orkoraptor)*; 3) first dorsal rib with honey-comb internal structure on its tubercle (absent in Australovenator, Megaraptor, and Murusraptor); 4) prominent anterior projection on the coracoid (absent in Fukuiraptor, Aerosteon, and Megaraptor)*; 5) coracoid without a subglenoid ridge (subglenoid ridge present in Aerosteon)*; 6) coracoid without a posteroventral fossa (posteroventral fossa present in Fukuiraptor, Aerosteon, and Megaraptor); and 7) and coracoid with ventromedial margin forming a dorsoventrally deep articular surface for the sternum (absent in Fukuiraptor, Aerosteon, and Megaraptor)*.

 

Alexis M. Aranciaga Rolando, Matias J. Motta, Federico L. Agnolín, Makoto Manabe, Takanobu Tsuihiji and Fernando E. Novas. 2022. A large Megaraptoridae (Theropoda: Coelurosauria) from Upper Cretaceous (Maastrichtian) of Patagonia, Argentina. Scientific Reports. 12, 6318. DOI: 10.1038/s41598-022-09272-z

Researchgate.net/publication/360214319_A_large_Megaraptoridae_from_Upper_Cretaceous_of_Patagonia_Argentina

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Alexis M. Aranciaga Rolando, Matias J. Motta, Federico L. Agnolín, Makoto Manabe, Takanobu Tsuihiji and Fernando E. Novas. 20xx. The Biggest Megaraptoridae (Theropoda: Coelurosauria) of South America. DOI: 10.21203/rs.3.rs-1152394/v1

Researchgate.net/publication/357264138_The_Biggest_Megaraptoridae_of_South_America

Abstract: Megaraptorans are a theropod clade distributed in former Gondwana landmasses and Asia. Most members of the clade are known from early Cretaceous to Turonian times whereas Maastrichtian megaraptorans are known just from isolated and poorly informative remains. The aim of present contribution is to describe a partial skeleton of a megaraptorid coming from Maastrichtian beds at Santa Cruz province, Argentina. This new taxon constitutes the most informative megaraptoran from post-Turonian beds. Phylogenetic analysis nested the new taxon together with South American megaraptorans in a monophyletic clade, whereas Australian and Asian members constitute successive stem groups. South American forms differ from more basal megaraptorans in several anatomical features and in being much larger and more robustly built. It is possible that the Cenomanian-Turonian extinction of carcharodontosaurids was allowed to megaraptorans to occupy the niche of top predators in South America.

KEYWORDS: Megaraptoridae, Maastrichtian, South America, Patagonia

[Paleontology • 2022] New Material of Phuwiangvenator yaemniyomi (Dinosauria: Theropoda) from the Type Locality: Implications for the early Evolution of Megaraptora

 

 Phuwiangvenator yaemniyomi  Samathi, Chanthasit & Sander, 2019

in Samathi, Suteethorn, Pradit & Suteethorn, 2022.

DOI: 10.1016/j.cretres.2021.105093 

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Highlights

• The new material (topotype) of Phuwiangvenator is here described.

• The additional autapomorphy from the new material is here present.

• Phuwiangvenator shows features shared with allosauroids and basal coelurosaurs.

• It appears to be intermediate between non-megaraptorid and megaraptorid theropods.

• This work provides information on the early evolution of the Megaraptora.

Abstract

Phuwiangvenator yaemniyomi is a mid-sized, early branching megaraptoran theropod from the Lower Cretaceous Sao Khua Formation of Phu Wiang Mountain, Khon Kaen Province, northeastern Thailand. The holotype includes dorsal and sacral vertebrae, lower legs, hand and foot elements. Here we describe new skeletal material pertaining to the same individual representing the holotype of Phuwiangvenator based on size, shape, and shared phylogenetic affinities. This material was recovered at the same quarry as the holotype and consists of an incomplete fibula, left and right metatarsals. A new autapomorphy observed from the new material is the presence of a long, deep fossa between the lateral and medial distal condyles of the metatarsal II that extends to the distal articular facet is visible in anterior view. The metatarsal III of Phuwiangvenator is relatively short, more similar to the proportion present in basal carcharodontosaur Concavenator than in the derived megaraptorans, but more gracile than other basal allosauroids. Its hindlimb proportions are similar to the basal carcharodontosaur Neovenator than other more derived megaraptorans and coelurosaurs. Phuwiangvenator shows a combination of features shared with allosauroids and basal coelurosaurs and appears to be “intermediate” between non-megaraptorid and megaraptorid theropods. The present work adds anatomical data on this theropod and provides information on the early evolution of the Megaraptora.

Keywords: Theropoda, Megaraptora, Phuwiangvenator, Early Cretaceous, Thailand

 

Adun Samathi, Suravech Suteethorn, Nakorn Pradit and Varavudh Suteethorn. 2022. New Material of Phuwiangvenator yaemniyomi (Dinosauria: Theropoda) from the Type Locality: Implications for the early Evolution of Megaraptora. Cretaceous Research. In Press, 105093. DOI: 10.1016/j.cretres.2021.105093  

งานวิจัยนี้ศึกษาชิ้นส่วนเพิ่มเติมของไดโนเสาร์กินเนื้อ ภูเวียงเวเนเตอร์ แย้มนิยมมี จากขอนแก่น คือชิ้นส่วนฝ่าตีนซ้ายและขวา พบว่า มันมีลักษณะทางกายวิภาคที่ก้ำกึ่งระหว่างพวกอัลโลซอรอยด์และเบซอลซีลูโรซอร์ ก็พอจะบอกได้ว่า ภูเวียงเวเนเตอร์ซึ่งอยู่ในกลุ่มเมกะแรปเตอร่า มีลักษณะที่โบราณเมื่อเทียบกับพวกเมกะแรปเตอร่ารุ่นหลังที่พบในอเมริกาใต้และออสเตรเลีย ...

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[Paleontology • 2018] Tratayenia rosalesi • A New Megaraptoran Theropod Dinosaur from the Upper Cretaceous Bajo de la Carpa Formation of northwestern Patagonia

Tratayenia rosalesi 

Porfiri, Juárez Valieri, Santos & Lamanna, 2018

  DOI: 10.1016/j.cretres.2018.03.014 
Illustration: Andrew McAfee

Abstract

We describe Tratayenia rosalesi gen. et sp. nov., a new megaraptoran theropod dinosaur from the Upper Cretaceous of Patagonia, Argentina. The holotype consists of a well-preserved, mostly articulated series of dorsal and sacral vertebrae, two partial dorsal ribs, much of the right ilium, and pubis and ischium fragments. It was found in a horizon of the Upper Cretaceous (Santonian) Bajo de la Carpa Formation of the Neuquén Group in the Neuquén Basin exposed near the town of Añelo in Neuquén Province of northwestern Patagonia. Phylogenetic analysis recovers Tratayenia within the Gondwanan megaraptoran subclade Megaraptoridae. The new taxon exhibits similarities to other megaraptorids such as Aerosteon riocoloradensis, Megaraptor namunhuaiquii, and Murusraptor barrosaensis, but also presents differences in the architecture of the dorsal and sacral vertebrae and the morphology of the ilium. Tratayenia is the first megaraptoran that unequivocally preserves the complete sequence of sacral vertebrae, thereby increasing knowledge of the osteology of the clade. Moreover, depending on the chronostratigraphic ages of the stratigraphically controversial megaraptorids Aerosteon and Orkoraptor burkei, as well as the phylogenetic affinities of several fragmentary specimens, the new theropod may be the geologically youngest megaraptorid or megaraptoran yet discovered. Tratayenia is also the largest-bodied carnivorous tetrapod named from the Bajo de la Carpa Formation, reinforcing the hypothesis that megaraptorids were apex predators in southern South America from the Turonian through the Santonian or early Campanian, following the extinction of carcharodontosaurids.

Keywords: Theropoda; Megaraptora; Megaraptoridae; Bajo de la Carpa Formation; Upper Cretaceous; Patagonia; Argentina

Figure 3. Preserved dorsal vertebrae and sacrum of  Tratayenia rosalesi gen. et sp. nov. (MUCP v1162). A, left lateral view. B, right lateral view.

Figure 2. Tentatively reconstructed body silhouette of  Tratayenia rosalesi gen. et sp. nov. showing the bones preserved in the holotype (MUCP v1162). Body regions not preserved in Tratayenia are based primarily on corresponding elements of the following megaraptorid species: cranium (Megaraptor namunhuaiquii, Murusraptor barrosaensis), mandible (Australovenator wintonensis, M. barrosaensis), postcranial axial skeleton (Aerosteon riocoloradensis, M. namunhuaiquii), appendicular skeleton (A. riocoloradensis, A. wintonensis, M. namunhuaiquii). Scale bar equals 1 m.

Systematic paleontology

 Dinosauria Owen, 1842
 Theropoda Marsh, 1881
 Tetanurae Gauthier, 1986

 Megaraptora Benson, Carrano, and Brusatte, 2010
 Megaraptoridae Novas, Agnolín, Ezcurra, Porfiri, and Canale, 2013

 Tratayenia rosalesi gen. et sp. nov. 

Etymology. Genus name for Tratayén, the locality where the holotype was collected; species name in honor of Diego Rosales, the discoverer of the specimen. 

....

Conclusions: 

Tratayenia rosalesi is a new taxon of megaraptoran theropod, the first to be described from the Santonian Bajo de la Carpa Formation of the Neuquén Group. Its discovery constitutes a previously unreported stratigraphic occurrence in the megaraptorid fossil record of northern Patagonia. The elevated pneumaticity and morphological resemblance of the axial and pelvic elements of Tratayenia to those of the megaraptorids Aerosteon riocoloradensis and Murusraptor barrosaensis suggests 851 particularly close relationships between these three taxa. Nevertheless, Tratayenia also exhibits a number of unique morphologies that justify the erection of a new taxon. The holotype is the first megaraptoran specimen to preserve a nearly complete sequence of middle and posterior dorsal vertebrae and the complete sacrum, which augments knowledge of serial variation in this area of the axial skeleton. Tratayenia rosalesi is the largest carnivorous taxon known from the Bajo de la Carpa Formation, and, like other Patagonian megaraptorids, was likely the apex predator in its paleoecosystem. 

Juan D. Porfiri, Rubén D. Juárez Valieri, Domenica D.D. Santos and Matthew C. Lamanna. 2018. A New Megaraptoran Theropod Dinosaur from the Upper Cretaceous Bajo de la Carpa Formation of northwestern Patagonia. Cretaceous Research. In Press.  DOI: 10.1016/j.cretres.2018.03.014

 researchgate.net/publication/323878344_A_new_megaraptoran_theropod_dinosaur_from_the_Upper_Cretaceous_Bajo_de_la_Carpa_Formation_of_northwestern_Patagonia

https://carnegiemnh.org/press/new-patagonian-predator-sheds-light-on-mysterious-meat-eating-dinosaur-group/

  

[Paleontology • 2016] Phylogenetic Relationships of the Cretaceous Gondwanan Theropods Megaraptor and Australovenator: the Evidence Afforded by Their Manual Anatomy

General comparisons of the manual elements of megaraptorid theropods are conducted with the aim to enlarge the morphological dataset of phylogenetically useful features within Tetanurae. Distinctive features of Megaraptor are concentrated along the medial side of the manus, with metacarpal I and its corresponding digit being considerably elongated. Manual ungual of digit I is characteristically enlarged in megaraptorids, but it is also transversely compressed resulting in a sharp ventral edge. We recognize two derived characters shared by megaraptorans and coelurosaurs (i.e., proximal end of metacarpal I without a deep and wide groove continuous with the semilunar carpal, and metacarpals I and II long and slender), and one derived trait similar to derived tyrannosauroids (i.e., metacarpal III length <0.75 length of metacarpal II). However, after comparing carpal, metacarpal and phalangeal morphologies, it becomes evident that megaraptorids retained most of the manual features present in Allosaurus. Moreover, Megaraptor and Australovenator are devoid of several manual features that the basal tyrannosauroid Guanlong shares with more derived coelurosaurs (e.g., Deinonychus), thus countering our own previous hypothesis that Megaraptora is well nested within Tyrannosauroidea. 

Keywords: Dinosauria, Theropoda, Megaraptoridae, Cretaceous, Argentina, Australia, morphology.

  

Figure 3. Left manus of Megaraptor namunhuaiquii (MUCPv 341) in dorsal view
 (A) and schematic representation (B) . Scale bar: 1 cm. 

Figure 6. Left manus in dorsal view of A, Dilophosaurus (modified from Welles, 1980); B, Allosaurus; C, Megaraptor; D, Sinocalliopteryx; E, Tanycolagreus (modified from Carpenter et al., 2005); F, Deinonychus (modified from Ostrom, 1969); G, Scipionyx (modified from Dal Sasso and Maganuco, 2011); H, Guanlong (modified from Xu et al., 2009); and I, Sinosauropteryx (modified from Currie and Chen, 2001). Not to scale. 

Abstract Novas, F.E., Aranciaga Rolando, A.M. and Agnolín, F.L. 2016. Phylogenetic Relationships of the Cretaceous Gondwanan Theropods Megaraptor and Australovenator: the Evidence Afforded by Their Manual Anatomy. Memoirs of Museum Victoria. 74: 49–61.

https://museumvictoria.com.au/pages/381424/049-061_MMV74_Novas_4_WEB.pdf

ResearchGate.net/publication/305642021_Phylogenetic_relationships_of_the_Cretaceous_Gondwanan_theropods_Megaraptor_and_Australovenator_the_evidence_afforded_by_their_manual_anatomy

[Paleontology • 2016] Murusraptor barrosaensis • A New Megaraptoran Dinosaur (Theropoda, Megaraptoridae) from the Late Cretaceous of Patagonia

Murusraptor barrosaensis  

Coria & Currie, 2016

  DOI: 10.1371/journal.pone.0157973 

Abstract

A skeleton discovered in the Upper Cretaceous Sierra Barrosa Formation (Turonian-Coniacian) of Neuquén Province, Argentina represents a new species of theropod dinosaur related to the long snouted, highly pneumatized Megaraptoridae. The holotype specimen of Murusraptor barrosaensis n.gen et n.sp. (MCF-PVPH-411) includes much of the skull, axial skeleton, pelvis and tibia. Murusraptor is unique in having several diagnostic features that include anterodorsal process of lacrimal longer than height of preorbital process, and a thick, shelf-like thickening on the lateral surface of surangular ventral to the groove between the anterior surangular foramen and the insert for the uppermost intramandibular process of the dentary. Other characteristic features of Murusraptor barrosaensis n.gen. et n. sp.include a large mandibular fenestra, distal ends of caudal neural spines laterally thickened into lateral knob-like processes, short ischia distally flattened and slightly expanded dorsoventrally. Murusraptor belongs to a Patagonian radiation of megaraptorids together with Aerosteon, Megaraptor and Orkoraptor. In spite being immature, it is a larger but more gracile animal than existing specimens of Megaraptor, and is comparable in size with Aerosteon and Orkoraptor. The controversial phylogeny of the Megaraptoridae as members of the Allosauroidea or a clade of Coelurosauria is considered analyzing two alternative data sets.

Systematic Paleontology

Dinosauria Owen, 1842

Theropoda Marsh, 1881

Tetanurae Gauthier, 1986

Megaraptora Benson, Carrano, Brusatte, 2010

Megaraptoridae Novas, Agnolin, Ezcurra, Porfiri, Canale 2013

Murusraptor barrosaensis new genus, new species

Etymology: “Murus” is a Latin term for “wall”, referring to the discovery of the specimen in the wall of a canyon; “barrosaensis” alludes to Sierra Barrosa, the locality where it was collected.

Holotype: Partial skeleton (Museo Carmen Funes MCF-PVPH-411) includes a complete braincase, lacrimal, prefrontal, postorbital, quadrate, pterygoid, ectopterygoid, teeth, twelve vertebrae, eleven thoracic ribs, one haemal arch, several gastralia, a manual ungual, complete left ilium, part of right ilium, proximal ends of the pubes, distal ends of the ischia, the right tibia, and a calcaneum (Fig 1).

Fig 1. A) Skull reconstruction of Murusraptor barrosaensis, MCF-PVPH-411. B) Body reconstruction

Both illustrations show recovered elements in white. Scale bars: A = 10 cm, B = 1 m.   DOI: 10.1371/journal.pone.0157973

Fig 3. Field photos of the excavation of MCF-PVPH-411 (Murusraptor barrosaensis).
A and B, the authors excavating the right ilium. C-F, different appendicular elements in their original burial positions before collection.

  DOI: 10.1371/journal.pone.0157973  

Diagnosis: Murusraptor barrosaensis is unique in having anterodorsal process of lacrimal longer than height of preorbital process, and a thick, shelf-like thickening on the lateral surface of surangular ventral to the groove between the anterior surangular foramen and the insert for the uppermost intramandibular process of the dentary. Two other characters are only known in Murusraptor; sacral ribs hollow and tubelike; short ischia distally flattened and slightly expanded dorsoventrally. These characters are equivocal because they are unknown in other members of the clade. Also, the following combination of diagnostic characters was obtained after running the phylogenetic analysis using TNT: Character 95, basipterygoid processes of the basisphenoid located anteroventrally, with basisphenoid recess opening posterodorsally (also present in coelophysids); Character 98, basisphenoid with a shallow embayment indentation between basal tubera and basipterygoid processes (also present in Cryolophosaurus and basal theropods); Character 216, rather straight chevrons (reversal to the plesiomorphic condition).

Rodolfo A. Coria and Philip J. Currie. 2016.  A New Megaraptoran Dinosaur (Dinosauria, Theropoda, Megaraptoridae) from the Late Cretaceous of Patagonia. PLoS ONE. 11(7): e0157973. DOI: 10.1371/journal.pone.0157973

Another Brick in the “Murus”: Meet the newest Megaraptoran theropod, Murusraptor http://blogs.plos.org/paleocomm/2016/07/20/another-brick-in-the-murus-meet-the-newest-megaraptoran-theropod-murusraptor