[Paleontology • 2025] Thilastikosuchus scutorectangularis • A New notosuchian (Crocodyliformes: Mesoeucrocodylia) from the Quiricó Formation, Lower Cretaceous, Sanfranciscana Basin, Brazil

Thilastikosuchus scutorectangularis

 de Carvalho, Santos, Pinto & Santucci, 2025 

DOI: doi.org/10.1080/02724634.2025.2452947 

   x.com/palaeodaniel

ABSTRACT

Notosuchians comprise a clade of mostly terrestrial crocodyliforms generally found in Cretaceous Gondwanan deposits. They evolved into many forms and some species show convergences with mammalian features such as the development of a high degree of heterodonty and multicuspid teeth. South American deposits concentrate the highest number of described notosuchian species, which is more than twice the number of taxa known from strata elsewhere. Here, a novel candidodontid notosuchian, Thilastikosuchus scutorectangularis, gen. et sp. nov., is presented and described, comprising a new monospecific genus and the oldest notosuchian record found in Brazil, and likely from South America. This new taxon lacks the sharp hypertrophied caniniform teeth of closely related forms, such as Malawisuchus and Pakasuchus, but shares the posterior molariform teeth with increasingly wider crowns and denticulated cingula. Additionally, the phylogenetic analysis with the inclusion of the new Brazilian material places Candidodontidae as the earliest notosuchian radiation, shedding new light into its origins.

Thilastikosuchus scutorectangularis, gen. et sp. nov.

Thilastikosuchus scutorectangularis gen. et sp. nov.

reconstruction by Felipe Elias

Joyce Celerino de Carvalho, Daniel Martins dos Santos, Ricardo Lourenço Pinto and Rodrigo Miloni Santucci. 2025. Anatomical Description and Systematics of A New notosuchian (Mesoeucrocodylia; Crocodyliformes) from the Quiricó Formation, Lower Cretaceous, Sanfranciscana Basin, Brazil. Journal of Vertebrate Paleontology. e2452947. DOI: doi.org/10.1080/02724634.2025.2452947  

  x.com/palaeodaniel/status/1891840889435115539

[Paleontology • 2025] Gondwanax paraisensis • A New “silesaurid” from the oldest Dinosauromorph-bearing Beds of South America provides insights into the early Evolution of Bird-line Archosaurs

Gondwanax paraisensis 

Müller, 2024  

DOI: 10.1016/j.gr.2024.09.007

Highlights: 

• One of the oldest dinosauromorphs is described.

• It is the earliest “silesaurid” with a sacrum composed of three vertebrae.

• The oldest episode of sympatry among “silesaurids” in South America is reported.

Abstract

Investigations regarding the early evolutionary history of bird-line archosaurs have undergone significant advancements in recent years. However, controversies remain, especially regarding the phylogenetic position of “silesaurids”. Whereas some hypotheses place these archosaurs as the sister-group to dinosaurs, others suggest that “silesaurids” are early ornithischian dinosaurs. Despite the phylogenetic disputes, “silesaurids” are a crucial group for comprehending the origins and early evolution of dinosaurs. In the present study, a new “silesaurid” from the Middle-Upper Triassic of Southern Brazil is described. Gondwanax paraisensis gen. et sp. nov. comes from the Dinodontosaurus Assemblage Zone of the Santa Maria Formation (Ladinian-Carnian boundary), representing one of the oldest “silesaurids” worldwide. Furthermore, Gondwanax paraisensis gen. et sp. nov is the oldest “silesaurid” with three sacral vertebrae, a feature usually observed in more derived forms. In addition, distinct from any other Triassic Pan-Aves, the new taxon bears an incipient fourth trochanter of the femur. This unique combination of features indicates a high diversity of locomotor strategies among early pan-avians. In addition, the co-occurrence of Gondwanax paraisensis gen. et sp. nov. and Gamatavus antiquus in the same Assemblage Zone represents the oldest evidence of sympatry among “silesaurids” in South America. Indeed, the unique combination of sacral and hindlimb features may suggest distinct behaviors for these species, potentially leading to niche differentiation within the same ecosystems.

Systematic palaeontology

Archosauria Cope, 1870 (sensu Gauthier & Padian, 2020)

Pan-Aves Gauthier and De Queiroz, 2001 (sensu Ezcurra et al., 2020)

Dinosauromorpha Benton, 1985 (sensu Ezcurra et al., 2020)

Gondwanax paraisensis gen. et sp. nov.

 

Rodrigo Temp Müller. 2024. A New “silesaurid” from the oldest Dinosauromorph-bearing Beds of South America provides insights into the early Evolution of Bird-line Archosaurs. Gondwana Research. In Press,  DOI: doi.org/10.1016/j.gr.2024.09.007

 

[Paleontology • 2024] Epoidesuchus tavaresae • A new Peirosauridae (Crocodyliformes: Notosuchia) from the Adamantina Formation (Bauru Group, Late Cretaceous), with a revised phylogenetic analysis of Sebecia

Epoidesuchus tavaresae

Ruiz, Queiroz, Martins, Godoy, Iori, Langer, Montefeltro & Bronzati, 2024

 

DOI: 10.1002/ar.25559 

x.com/PedroLGodoy 

 Artwork by Guilherme Gehr

Abstract

Peirosauridae (Crocodyliformes, Notosuchia) is one of the fossil lineages of crocodyliforms ubiquitous in the Cretaceous deposits of the Bauru Basin. Here, we describe a new species of a longirostrine Peirosauridae from the Adamantina Formation (Bauru Basin, Late Cretaceous). The specimen consists of a partially preserved skull with a cranial roof, interorbital region, and fragments of the posterior portion of the rostrum, including the prefrontal and lacrimal; left hemimandible, with 14 alveoli and 12 teeth; and a single cervical rib fragment. The specimen is associated with Peirosauridae by three cranial synapomorphies, and it can be assigned to a new genus and species by presenting seven cranial and one tooth apomorphies. To clarify the position of the new taxon, an updated phylogenetic analysis was performed with increased sampling of taxa of Notosuchia, especially Peirosauridae, and phylogenetically relevant characters. Our results indicated the monophyly of Peirosauridae, formed by two main lineages, the oreinirostral and presumably terrestrial Peirosaurinae and the longirostrine and presumably semi-aquatic Pepesuchinae. The recovering of both lineages as distinct entities was also reinforced through a morphospace analysis. Pepesuchinae were notable by exploring a position of the morphospace not explored by any other Notosuchia. Their longer rostra and the assumption of them being gradually specialized to aquatic habits reflects the unique diversity of these crocodyliforms through the Cretaceous deposits of South America and Africa.

Keywords: Bauru Basin, freshwater Tetrapoda, Mesoeucrocodylia, Pepesuchinae, South America

Epoidesuchus tavaresae, from the Adamantina Formation (Late Cretaceous), a new pepesuchine peirosaurid, which was long-snouted and semiaquiatic.

  paleoart by Guilherme Gehr

 Juan V. Ruiz, Marcos V. L. Queiroz, Kawan C. Martins, Pedro L. Godoy, Fabiano V. Iori, Max C. Langer, Felipe C. Montefeltro and Mario Bronzati. 2024. A new Peirosauridae (Crocodyliformes, Notosuchia) from the Adamantina Formation (Bauru Group, Late Cretaceous), with a revised phylogenetic analysis of Sebecia. The Anatomical Record. DOI: doi.org/10.1002/ar.25559 

 x.com/PedroLGodoy/status/1829467655188689194

Graphical Abstract: This study presents a new species of Peirosauridae, Epoidesuchus tavaresae, from the Adamantina Formation, Cretaceous of Brazil. In the most complete phylogenetic analysis of this lineage conducted to date, Peirosauridae was recovered encompassing two main lineages, Peirosaurinae (usually orenirostrine forms) and Pepesuchinae (usually longirostrine forms). 

[Paleontology • 2024] Araripesuchus manzanensis • A New Species of Araripesuchus with durophagous dentition increases the ecological disparity among uruguaysuchid crocodyliforms

Araripesuchus manzanensis

Dumont, Pol, Bona & Apesteguía. 2024. 

DOI: 10.1080/14772019.2024.2373987 

 

Abstract

Notosuchia is a group of crocodyliforms with mostly terrestrial habits that lived during the Mesozoic and up to the Miocene. Within this group Uruguaysuchidae is so far represented by eight species, six of them clustered in the genus Araripesuchus. Two species of this genus, A. patagonicus and A. buitreraensis, come from different localities in Patagonia (Argentina) from the Candeleros Formation (Cenomanian age). Here we present a third species of Araripesuchus from this formation. The new species comes from the same locality as Araripesuchus buitreraensis, but differs in numerous features including the presence of different molariform teeth. The new species was included in a phylogenetic analysis and, in agreement with previous analyses, Uruguaysuchidae is recovered as monophyletic and placed within Notosuchia as the sister clade of Peirosauridae. Uruguaysuchidae includes all species of Araripesuchus as well as Anatosuchus minor and Uruguaysuchus aznarezi. The new species adds new information to the ecological diversity of the group its bulbous molariforms with a quadrangular occlusal surface bounded by mamelons is interpreted as indicative of a durophagous diet, suggesting the presence of niche partitioning between the two sympatric species A. manzanensis and A. buitreraensis.  

Keywords: Notosuchia, Araripesuchus, Patagonia, La Buitrera, durophagous diet, niche partitioning

 

María Lucila Fernández Dumont, Diego Pol, Paula Bona and Sebastián Apesteguía. 2024. A New Species of Araripesuchus with durophagous dentition increases the ecological disparity among uruguaysuchid crocodyliforms. Journal of Systematic Palaeontology. 22(1);  2373987. DOI: doi.org/10.1080/14772019.2024.2373987 

[Paleontology • 2024] Benggwigwishingasuchus eremicarminis • A New pseudosuchian (Archosauria: Pseudosuchia) from the Favret Formation of Nevada reveals that Archosauriforms occupied Coastal Regions globally during the Middle Triassic

Benggwigwishingasuchus eremicarminis 

Smith, Klein, Sander & Schmitz, 2024 

DOI: 10.1098/rsbl.2024.0136

Abstract

Recent studies suggest that both stem- and crown-group Archosauria encompassed high ecological diversity during their initial Triassic radiation. We describe a new pseudosuchian archosaur, Benggwigwishingasuchus eremicarminis gen. et sp. nov., from the Anisian (Middle Triassic) Fossil Hill Member of the Favret Formation (Nevada, USA), a pelagic setting in the eastern Panthalassan Ocean characterized by the presence of abundant ammonoids and large-bodied ichthyosaurs. Coupled with archosauriforms from the eastern and western Tethys Ocean, Benggwigwishingasuchus reveals that pseudosuchians were also components of Panthalassan ocean coastal settings, establishing that the group occupied these habitats globally during the Middle Triassic. However, Benggwigwishingasuchus, Qianosuchus, and Ticinosuchus (two other pseudosuchians known from marine sediments) are not recovered in a monophyletic group, demonstrating that a nearshore marine lifestyle occurred widely across Archosauriformes during this time. Benggwigwishingasuchus is recovered as part of an expanded Poposauroidea, including several taxa (e.g. Mandasuchus, Mambawakalae) from the Middle Triassic Manda Beds of Tanzania among its basally branching members. This implies a greater undiscovered diversity of poposauroids during the Early Triassic, and supports that the group, and pseudosuchians more broadly, diversified rapidly following the End-Permian mass extinction.

Class Reptilia Linnaeus, 1758

Archosauriformes  

Archosauria  

Pseudosuchia  

Poposauroidea  

Benggwigwishingasuchus eremicarminis gen. et sp. nov.
Holotype skeleton (LACM-DI 158616) (a) (pelvis block mirrored for articulation); and interpretive drawing (b)  

Genus Benggwigwishingasuchus

Benggwigwishingasuchus eremicarminis gen. et sp. nov.

  Holotype: LACM-DI 158616, a partially articulated skeleton, including some cranial elements but most of the axial column, girdles and limbs.

  Diagnosis: Mid-sized pseudosuchian (total length: approximately 1.5 m; femur length: 17.75 cm) diagnosed by the following unique combination of characters (*indicates autapomorphy, †indicates autapomorphy inferred from phylogenetic analysis): semilunate eminence on middle of ventral ramus of prefrontal*; ventral ramus of prefrontal broadly exposed in lateral view, extensive ventrally and excludes lacrimal from orbit; supratemporal fossa well-exposed dorsally on parietal; high cervical vertebrae count (10–11); low dorsal vertebrae count (10–11)*; dorsal vertebrae with well-developed laminae and deep infradiapophyseal fossae; anterior caudal vertebrae with well-developed, spatulate ribs; anterior caudal ribs asymmetrical in dorsal view, with diagonal bevel on posterolateral edge*; weakly sinusoidal fibular shaft; metatarsal IV longer than metatarsal III†; metatarsal IV subequal in length to metatarsal II†; robust lateral plantar tubercle on ventral face of metatarsal V; dorsal osteoderms in one-to-one, mirrored alignment in dorsal aspect†; osteoderms with indentations creating an ‘hourglass’ waisting in dorsal view*; osteoderms with multiple short spikes on lateral and medial edges.

  Etymology: The generic name combines ‘Benggwi Gwishinga’ from the Shoshone term for ‘catching fish’, with ‘suchus’, the Greek term for Sobek, the Egyptian crocodile-headed god. The specific epithet combines the Latin ‘erema’ and ‘carminis’, meaning ‘desert song’, and honours Elaine Kramer and Monica Shaffer, and their love of the palaeontology, museums, and opera of the southwestern USA. The binomen is intended to translate roughly as ‘Fisherman Croc's desert song’.

Middle Triassic palaeogeographic map with localities of Archosauriformes known from marine settings.

  Locality and age: Fossil Hill Member of the Favret Formation, Favret Canyon, Augusta Mountains, Pershing County, Nevada, USA. The type locality, LACM LOC 8057, is near the top of the north slope of Favret Canyon at an altitude of 1911 m. The horizon pertains to the Frechites occidentalis Zone, which is late Anisian (Middle Triassic) in age.

Nathan D. Smith, Nicole Klein, P. Martin Sander and Lars Schmitz. 2024. A New pseudosuchian from the Favret Formation of Nevada reveals that Archosauriforms occupied Coastal Regions globally during the Middle Triassic. Biol. Lett. 2020240136. DOI: doi.org/10.1098/rsbl.2024.0136

[Paleontology • 2024] Parvosuchus aurelioi • A New small-sized predatory pseudosuchian Archosaur (Pseudosuchia: Gracilisuchidae) from the Middle-Late Triassic of Southern Brazil

 Parvosuchus aurelioi  

Müller, 2024 

   

DOI: 10.1038/s41598-024-63313-3

 Artwork by Matheus Fernandes.

Abstract

Before the rise of dinosaurs and pterosaurs, pseudosuchians—reptiles from the crocodilian lineage—dominated the Triassic land ecosystems. This lineage diversified into several less inclusive clades, resulting in a wide ecomorphological diversity during the Middle and Late Triassic. Some giant pseudosuchians occupied the top of the trophic webs, while others developed extensive bony armor as a defense mechanism, which later evolved as a convergence in the avemetatarsalian lineage. On the other hand, there were groups like the Gracilisuchidae, which was composed of carnivorous forms with lightweight build and less than 1 m in length. The fossil record of gracilisuchids is geographically restricted to China and Argentina, with one ambiguous record from Brazil. In the present study, the first unambiguous gracilisuchid from Brazil is described. Parvosuchus aurelioi gen. et sp. nov. comes from the Dinodontosaurus Assemblage Zone of the Santa Maria Formation, which is associated with the Ladinian-Carnian boundary. Composed of a complete cranium, vertebrae, pelvic girdle and hindlimbs, the new species nests with Gracilisuchus stipanicicorum and Maehary bonapartei in a phylogenetic analysis. Its discovery fills a taxonomic gap in Brazilian pseudosuchian fauna and reveals the smallest known member of this clade from the Dinodontosaurus Assemblage Zone, highlighting the diversity of pseudosuchians during the moment that preceded the dawn of dinosaurs.

 

Skull and lower jaws of Parvosuchus aurelioi gen. et sp. nov.
Holotype (CAPPA/UFSM 0412)
 from the Pinheiros-Chiniquá Sequence (Ladinian-Carnian boundary) of the Santa Maria Supersequence, southern Brazil. 

Provenance of Parvosuchus aurelioi gen. et sp. nov. 
(a) Location and geological context of the Linha Várzea 2 site, Paraíso do Sul, Rio Grande do Sul, Brazil. (b) General view of the Linha Várzea 2 site (taken in January 2023).
(c) Hypothetical reconstruction of the skeleton of the Parvosuchus aurelioi gen. et sp. nov. depicting (in orange) the preserved portions of CAPPA/UFSM 0412. Unpreserved portions are based on the skeletal reconstruction of Gracilisuchus stipanicicorum by Jorge González.

Systematic paleontology

Archosauria Cope, 1869

Pseudosuchia Zittel, 1887–1890

Gracilisuchidae Butler et al., 2014

Parvosuchus aurelioi gen. et sp. nov. 

Holotype: CAPPA/UFSM 0412, a partial skeleton, including a skull with lower jaws, 11 dorsal vertebrae, two sacral vertebrae, a complete pelvic girdle, both femora (lacking the distal portion), partial left tibia, partial left fibula, and left calcaneum.

Etymology: The genus name combines the Latin word “parvus” (= small) and the Greek word “suchus” (= crocodile). The specific epithet honors Pedro Lucas Porcela Aurélio for his passion for paleontology and prospecting, as well as for having discovered the fossil material described here.

Results of the phylogenetic analysis and diversity of the Dinodontosaurus Assemblage Zone of Brazil. (a) Time-calibrated reduced strict consensus tree depicting the phylogenetic position of Parvosuchus aurelioi gen. et sp. nov. Number on nodes represent Bremer support values higher than 1. The temporal bars for each OTU represent the maximum and minimum ages of each geological unit. Divergence times set as approximately 1 million years. (b) Percentage of taxonomic groups recorded in the Dinodontosaurus Assemblage Zone according to the number of species. (c) Approximate body length of pseudosuchian species from the Dinodontosaurus ZA.

Artistic representation of a Middle-Late Triassic landscape of southern Brazil.
(a) A large Prestosuchus chiniquensis feeds on the carcass of a dicynodont while individuals of Parvosuchus aurelioi gen. et sp. nov. compete for scraps. (b) and (c) depict details of individuals of Parvosuchus aurelioi gen. et sp. nov. Artwork by Matheus Fernandes.

Rodrigo T. Müller. 2024. A New small-sized predatory pseudosuchian Archosaur from the Middle-Late Triassic of Southern Brazil. Scientific Reports. 14, 12706. DOI: 10.1038/s41598-024-63313-3

[Paleontology • 2024] Caipirasuchus catanduvensis • A New Species of vocalizing Crocodyliform (Notosuchia: Sphagesauridae) from the Late Cretaceous of Brazil

 

Caipirasuchus catanduvensis 

 Iori, Ghilardi, Fernandes & Dias, 2024

DOI: 10.1080/08912963.2024.2364332

 x.com/AlineMGhilardi

ABSTRACT

Caipirasuchus is a genus of sphagesaurid notosuchian from the Bauru Basin (Upper Cretaceous), southeast Brazil. They were small-sized herbivorous/omnivorous animals, that measured around 1 metre in length, and had a wide diversity and geographical dispersion in the basin. Here, we diagnosed the 6th species of the genus, originating from sandstones of the Adamantina Formation in the municipality of Catanduva, São Paulo State. Caipirasuchus presents a significant variation in the morphology of structures in the choana region. In particular, the new species has chambers in the wings of the pterygoids that connect with an extension of the airways, suggesting a region of resonance used in vocalisation. The different palatal structures in Caipirasuchus may be related to distinct bioacoustic signatures and indicate apossible improvement in the social organisation of Caipirasuchus.

KEYWORDS: Crocodylomorpha, crocodyliformes, Adamantina formation, bioacoustics, vocalization, Bauru Basin

Caipirasuchus catanduvensis 

Fabiano V. Iori, Aline M. Ghilardi, Marcelo A. Fernandes and Willian A.F. Dias. 2024. A New Species of vocalizing Crocodyliform (Notosuchia, Sphagesauridae) from the Late Cretaceous of Brazil. Historical Biology: An International Journal of Paleobiology. DOI: 10.1080/08912963.2024.2364332

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[Paleontology • 2024] Garzapelta muelleri • A New aetosaur (Archosauria: Pseudosuchia) from the Late Triassic (middle Norian) middle Cooper Canyon Formation, Dockum Group, Texas, USA, and its implications on our understanding of the morphological disparity of the aetosaurian dorsal carapace

 Garzapelta muelleri

 Reyes, Martz &  Small, 2024

  

DOI: 10.1002/ar.25379

 twitter.com/WAReyes6 

 twitter.com/AnatRecord

 

Abstract

The Late Triassic Dockum Group in northwestern Texas preserves a rich diversity of pseudosuchian taxa, particularly of aetosaurs. In this contribution, we present Garzapelta muelleri gen. et sp. nov., a new aetosaur from the Late Triassic middle Cooper Canyon Formation (latest Adamanian–earliest Revueltian teilzones) in Garza County, Texas, based on an associated specimen that preserves a significant portion of its dorsal carapace. The carapace of G. muelleri exhibits a striking degree of similarity between that of the paratypothoracin Rioarribasuchus chamaensis and desmatosuchins. We quantitatively assessed the relationships of G. muelleri using several iterations of the matrix. Scoring the paramedian and lateral osteoderms of G. muelleri independently results in conflicting topologies. Thus, it is evident that our current matrix is limited in its ability to discern the convergence within this new taxon and that our current character lists are not fully accounting for the morphological disparity of the aetosaurian carapace. Qualitative comparisons suggest that G. muelleri is a Rioarribasuchus-like paratypothoracin with lateral osteoderms that are convergent with those of desmatosuchins. Although the shape of the dorsal eminence, and the presence of a dorsal flange that is rectangular and proportionately longer than the lateral flange are desmatosuchin-like features of G. muelleri, the taxon does not exhibit the articulation style between the paramedian and lateral osteoderms which diagnose the Desmatosuchini (i.e., a rigid interlocking contact, and an anteromedial edge of the lateral osteoderm that overlaps the adjacent paramedian osteoderm).

Keywords: Aetosaur, Dockum Group, Late Triassic, Revueltian, Texas

William A. Reyes, Jeffrey W. Martz, Bryan J. Small. 2024. Garzapelta muelleri gen. et sp. nov., A New aetosaur (Archosauria: Pseudosuchia) from the Late Triassic (middle Norian) middle Cooper Canyon Formation, Dockum Group, Texas, USA, and its implications on our understanding of the morphological disparity of the aetosaurian dorsal carapace. The Anatomical Record. DOI: 10.1002/ar.25379

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 twitter.com/AnatRecord/status/1745792749549330691

[Paleontology • 2023] A saurischian (Archosauria: Dinosauria) ilium from the Upper Triassic of southern Brazil and the Rise of Herrerasauria

CAPPA/UFSM 0373, left ilium

in Garcia, Cabreira, da Silva, Pretto & Müller, 2023.

DOI: 10.1002/ar.25342 

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Abstract

The Carnian (Upper Triassic) rocks of the Candelária Sequence present a rich record of dinosaurs, including some of the oldest known dinosaurs worldwide. In this contribution we describe the first unequivocal dinosaur from the Pivetta site, located in the Restinga Sêca municipality, Southern Brazil. The specimen CAPPA/UFSM 0373 is an isolated but well-preserved left ilium. A thorough examination of the specimen's anatomy and a phylogenetic analysis provides evidence that CAPPA/UFSM 0373 belongs to the Herrerasauria. We were able to identify several similarities with potential non-herrerasaurid herrerasaurians (e.g., Tawa hallae, “Caseosaurus crosbyensis”), which were previously only known from North American deposits. In contrast, herrerasaurids (e.g., Herrerasaurus ischigualastensis) are almost exclusively known from South America. Our results support the nesting of CAPPA/UFSM 0373 as an early-diverging herrerasaurian. Furthermore, this is potentially the first record of a non-herrerasaurid herrerasaurian in unambiguous Carnian beds, suggesting a hidden diversity of dinosaurs in the Carnian rocks of the Candelária Sequence, which can be revealed even by fragmentary specimens.

Mauricio Silva Garcia, Sérgio Furtado Cabreira, Lúcio Roberto da Silva, Flávio Augusto Pretto and Rodrigo Temp Müller. 2023. A saurischian (Archosauria, Dinosauria) ilium from the Upper Triassic of southern Brazil and the Rise of Herrerasauria. The Anatomical Record. DOI: 10.1002/ar.25342

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[Paleontology • 2023] Amanasaurus nesbitti • A New silesaurid (Archosauria: Silesauridae) from Carnian Beds of Brazil fills A Gap in the Radiation of Avian line Archosaurs

Amanasaurus nesbitti 

 Müller & Garcia, 2023

 DOI: 10.1038/s41598-023-32057-x 

 Researchgate.net/publication/369946312

Abstract

Comprising the oldest unequivocal dinosauromorphs in the fossil record, silesaurs play an important role in the Triassic radiation of dinosaurs. These reptiles provide the main source of information regarding the ancestral body plan of dinosaurs, as well as the basis for biogeographic models. Nevertheless, the co-occurrence of silesaurs and the oldest unequivocal dinosaurs is rare, which hampers reliable ecological inferences. Here we present the first species of silesaur from the oldest unequivocal dinosaur-bearing beds from Brazil. Amanasaurus nesbitti gen. et sp. nov. possesses a unique set of femoral traits among silesaurs, including the oldest occurrence of an anterior trochanter separated by the femoral shaft by a marked cleft. Its femoral length indicates that the new species rivals in size with most coeval dinosaurs. This find challenges the assumption that in faunas where silesaurs and unambiguous dinosaurs co-occurred, silesaurs were relatively smaller. Moreover, the presence of dinosaur-sized silesaurs within ecosystems with lagerpetids, sauropodomorphs and herrerasaurids reinforces the complex scenario regarding the early radiation of Pan-Aves. Silesaurs—independent of their phylogenetic position—persisted during most of the Triassic Period, with its plesiomorphic body size advancing through the dawn of dinosaurs, instead of silesaur lineages decrease in body size through time.

Systematic paleontology

Archosauria Cope, 1869

Pan-Aves Gauthier & de Queiroz, 2001

Dinosauromorpha Benton, 1985

Silesauridae Nesbitt et al., 2010

Amanasaurus nesbitti gen. et sp. nov. 

Diagnosis: Amanasaurus nesbitti differs from all other known silesaurs with comparable material in (*local autapomorphies): posteromedial tuber of the femoral head reduced to absent; ventral margin of the anteromedial tuber exceeding the femoral head margin; presence of a fossa trochanterica; absence of a raised anterolateral scar; presence of a semi-circular scar on the posterodorsal surface of the femoral head*; cleft between the proximal tip of the anterior trochanter and the femoral shaft ...

Etymology: The genus combines the Tupi word “amana” (= rain) and the Greek “saurus” (= lizard), referring to the Carnian pluvial episode. The specific epithet honors Dr. Sterling J. Nesbitt, a prominent North American paleontologist, for his contribution and studies on silesaurs and Triassic archosaurs.

Rodrigo T. Müller and Maurício S. Garcia. 2023. A New silesaurid from Carnian Beds of Brazil fills A Gap in the Radiation of Avian line Archosaurs. Scientific Reports.  13: 4981. DOI: 10.1038/s41598-023-32057-x

  Researchgate.net/publication/369946312_A_new_silesaurid_from_Carnian_beds_of_Brazil

 www.ufsm.br/2023/04/14/paleontologos-descobrem-nova-especie-pre-historica 

[Paleontology • 2023] Samsarasuchus pamelae • A New archosauriform Species (Archosauriformes: Proterosuchidae) from the Panchet Formation of India and the Diversification of Proterosuchidae after the end-Permian Mass Extinction

Samsarasuchus pamelae 

Ezcurra, Bandyopadhyay, Sengupta, Sen, Sennikov, Sookias, Nesbitt & Butler, 2023

 DOI: 10.1098/rsos.230387 

 twitter.com/ButlerLabBham

artwork: Gabriel Lio

Abstract

Proterosuchidae represents the oldest substantial diversification of Archosauromorpha and plays a key role in understanding the biotic recovery after the end-Permian mass extinction. Proterosuchidae was long treated as a wastebasket taxon, but recent revisions have reduced its taxonomic content to five valid species from the latest Permian of Russia and the earliest Triassic (Induan) of South Africa and China. In addition to these occurrences, several isolated proterosuchid bones have been reported from the Induan Panchet Formation of India for over 150 years. Following the re-study of historical specimens and newly collected material from this unit, we erect the new proterosuchid species Samsarasuchus pamelae, which is represented by most of the presacral vertebral column. We also describe cf. proterosuchid and proterosuchid cranial, girdle and limb bones that are not referred to Samsarasuchus pamelae. Phylogenetic analyses recovered Samsarasuchus pamelae within the new proterosuchid clade Chasmatosuchinae. The taxonomic diversity of Proterosuchidae is substantially expanded here, with at least 11 nominal species and several currently unnamed specimens, and a biogeographical range encompassing present-day South Africa, China, Russia, India, Brazil, Uruguay and Australia. This indicates a broader taxonomic, phylogenetic and biogeographic diversification of Proterosuchidae than previously thought in the aftermath of the end-Permian mass extinction.

Keywords: phylogeny, biogeography, Proterosuchidae, Archosauromorpha, Induan, Mesozoic

 

Diapsida Osborn, 1903

Archosauromorpha von Huene, 1946

Archosauriformes Gauthier, Kluge & Rowe, 1988

Proterosuchidae von Huene, 1908 sensu Ezcurra, Butler & Gower, 2013

Chasmatosuchinae nov.

 

 Phylogenetic definition: The most inclusive clade containing Chasmatosuchus rossicus von Huene, 1940, but not Proterosuchus fergusi Broom, 1903, ‘Chasmatosaurus’ yuani Young, 1936, Proterosuchus alexanderi (Hoffman, 1965), Proterosuchus goweri Ezcurra & Butler, 2015, Erythrosuchus africanus Broom, 1905, or Alligator mississippiensis Daudin, 1802. This is a maximum clade definition.

   Composition: The composition is based on the reference phylogeny. Chasmatosuchinae includes Chasmatosuchus rossicus, Jaikosuchus magnus, Samsarasuchus pamelae, Archosaurus rossicus, Gamosaurus lozovskii, Tsylmosuchus spp., Vonhuenia friedrichi and indeterminate specimens from the Arcadia Formation and Bulgo Sandstone of the Sydney Basin of Australia and the Sanga do Cabral Formation of Brazil.

 Diagnosis: Chasmatosuchines differ from other proterosuchids in the presence of anterior–middle and sometimes posterior postaxial cervical vertebrae with distally restricted transverse expansion of the neural spines (not mammillary process); third to eighth or ninth presacral vertebrae with diagonal, anterodorsally-to-posteroventrally oriented ridge that reaches the base of the prezygapophysis and is not connected to the diapophysis on the lateral surface of the neural arch; fourth to eight presacral vertebrae with posterior expansion of the dorsal portion of the neural spine, resulting in a posterodorsally tilted posterior margin set at an angle higher than 15° with respect to the anterior margin of the neural spine in lateral view; ninth presacral centrum with a ventral keel and anterior caudal vertebrae with surface lateral to the base of the neural spine with a very deep fossa, well-defined laterally and that transversely constricts the anterior half of the neural spine.

  Geographical and stratigraphic occurrence of specimens of Samsarasuchus pamelae gen. et sp. nov. and Panchet cf. proterosuchid and proterosuchid specimens.
(a) Gondwana basins of peninsular India showing the studied area of the Damodar Basin, which has yielded specimens of Samsarasuchus pamelae; (b) geological map showing the location of the Deoli locality that yielded Samsarasuchus pamelae bones discovered by the 2015 fieldtrip; (c) composite stratigraphic column of the Panchet Formation, including the occurrence of the Samsarasuchus pamelae bones discovered by the 2015 fieldtrip; (d) general overview of the sandstones of the Deoli locality on the shore of the Damodar River (January 2015); and (e) close up of the holotype of Samsarasuchus pamelae (ISIR 1091) as found in the field.

Samsarasuchus pamelae gen. et sp. nov.

Diagnosis: Samsarasuchus pamelae is a chasmatosuchine proterosuchid that differs from other non-archosaurian archosauriforms in the following autapomorphies (among non-archosaurian archosauriforms) present in its holotype (ninth cervical vertebra): posteriormost cervical vertebra (ninth cervical vertebra) with two pairs (i.e. four in total) of mammillary processes on the neural spine; and posteriormost cervical vertebra (ninth cervical vertebra) with dorsolaterally oriented mammillary processes on the anterior region of the neural spine. In addition, the holotype of Samsarasuchus pamelae and the other postaxial cervical and anterior–middle dorsal vertebrae referred to this species share the following unique combination of character states that allow the species to be distinguished from other non-erythrosuchid, non-eucrocopod archosauriform nominal species: third cervical to anterior dorsal vertebrae ....

Etymology: The genetic epithet is formed by the Sanskrit word ‘Saṁsāra’ (Samsara) that in Hinduism is related to the cycle of re-birth, existence and death, and ‘Σοῦχος’ (Suchus), which is the name of the Egyptian crocodile-headed deity Sebek or Sobek in ancient Greek, referring to the re-birth of ecosystems after the end-Permian mass extinction and the most common ending (-suchus) of archosauromorph genera. The specific epithet is for the first name of the British palaeontologist Pamela Lamplugh Robinson (1919–1994) in honour of her contributions to Indian vertebrate palaeontology and especially for having prompted a renewed interest in the vertebrate palaeontology of the Panchet Formation in the 1960s after a long gap in research since the end of the ninteenth century. In addition, Pamela Robinson led the fieldtrip that resulted in the discovery of several referred specimens of this new proterosuchid species (NHMUK collection).

 

Martín D. Ezcurra, Saswati Bandyopadhyay, Dhurjati P. Sengupta, Kasturi Sen, Andrey G. Sennikov, Roland B. Sookias, Sterling J. Nesbitt and Richard J. Butler. 2023. A New archosauriform Species from the Panchet Formation of India and the Diversification of Proterosuchidae after the end-Permian Mass Extinction. R. Soc. open sci. 10230387. DOI: 10.1098/rsos.230387

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