Several genera have been assigned to Baurusuchidae. Baurusuchus was the first, being the namesake of the family. Remains of Baurusuchus have been found from the Late CretaceousBauru Group of Brazil in deposits that are Turonian - Santonian in age.[3] In addition to Baurusuchus, five other South American crocodyliforms have been assigned to Baurusuchidae: Campinasuchus, Cynodontosuchus, Pissarrachampsa, Stratiotosuchus, and Wargosuchus. Cynodontosuchus was the first known baurusuchid, named in 1896 by English paleontologist Arthur Smith Woodward, although it was only recently assigned to Baurusuchidae.[4]Wargosuchus was described in 2008.[5]Cynodontosuchus and Wargosuchus are known only from fragmentary remains. Both genera are from the Santonian of Argentina.
A fourth genus, Stratiotosuchus, was assigned to Baurusuchidae in 2001. Pabwehshi is the youngest genus that has been assigned to Baurusuchidae, and is from the Maastrichtian of Pakistan.[6] It was named in 2001 but has since been reassigned as a basal member of Sebecia.[7]
A new genus, Campinasuchus, was assigned to the family in May, 2011. It is known from the Turonian-Santonian Adamantina Formation of the Bauru Basin of Brazil.[8] Soon after, the new genus Pissarrachampsa was named from the Campanian–Maastrichtian Vale do Rio do Peixe Formation, also in the Bauru Basin.
Phylogeny
The family Baurusuchidae was named by BrazilianpaleontologistLlewellyn Ivor Price in 1945 to include Baurusuchus.[9] In 1946, American paleontologist Edwin Harris Colbert erected the group Sebecosuchia, which united Baurusuchidae with the family Sebecidae (represented by the genus Sebecus).[10] Both Baurusuchus and Sebecus have deep snouts and ziphodont dentitions (teeth that are serrated and laterally compressed).[11] Other forms were later found that had a close appearance to these two genera, among them Cynodontosuchus, Stratiotosuchus, and Wargosuchus. Several features were used to unite these groups: a deep snout, a ziphodont dentition, a curved tooth row, an enlarged canine-like dentary tooth that fits into a deep notch in the upper jaw, and a groove on the lower jaw.[12]
Many phylogenetic analyses within the past decades have supported a close relationship between the two families.[11] Baurusuchids and sebecosuchids are both early members of the cladeMetasuchia, which includes the subgroups Notosuchia (mainly terrestrial crocodyliforms) and Neosuchia (larger, often semiaquatic crocodyliforms, including living crocodylians). Sebecosuchians, which include both baurusuchids and sebecosuchids, were found to be closely related to notosuchians in several studies.[13] The new genera Iberosuchus and Eremosuchus were later assigned to Baurusuchidae, and phylogenetic analyses encompassing these taxa continued to find Baurusuchidae to be closely related to Sebecidae.[14] Both families were allied with notosuchians in the larger group Ziphosuchia, composed of ziphodont crocodyliforms. More recently, sebecosuchians - including baurusuchids - have been placed within Notosuchia as derived members of the clade. Below is a modified cladogram from Ortega et al. (2000) placing baurusuchids within Notosuchia:[15]
In 2004, the superfamily Baurusuchoidea was established to include baurusuchids and sebecids. Phylogenetically, Baurusuchoidea was defined as the most recent common ancestor of Baurusuchus and Sebecus and all of its descendants while Baurusuchidae was defined as the most recent common ancestor of Baurusuchus and Stratiotosuchus and all of its descendants.[16]
In a 2005 analysis, Sebecidae was found to be a paraphyletic grouping, or a grouping that includes some descendants of a common ancestor but not all. Sebecids formed an assemblage of basal sebecosuchians, while baurusuchids remained a valid grouping of derived sebecosuchians. Below is a modified cladogram from Turner and Calvo (2005):[17]
Later studies noted many features that distinguished baurusuchids from sebecosuchids. Sebecosuchids were often considered to be more closely related to Neosuchia, a group that includes modern crocodylians, while baurusuchids were thought to be a more distantly related clade.[18] In a 1999 phylogenetic analysis, Baurusuchus formed a clade with notosuchians to the exclusion of other ziphosuchians.[19] This placement has been upheld by recent analyses, which place Baurusuchus within Notosuchia.[20]
In 2007, a new clade called Sebecia was erected.[7] Sebecia included sebecids and peirosaurids. Peirosauridae, a family of small terrestrial crocodyliforms, had often been placed in or near Neosuchia in previous studies. The assignment of sebecids to Sebecia placed the family closer to Neosuchia than Notosuchia. In this study, baurusuchids were split up, with Baurusuchus placed as a more basal metasuchian and the remaining baurusuchids (Bretesuchus and Pabwehshi) placed as sebecians. Therefore, the family Baurusuchidae was paraphyletic. Below is a modified cladogram from Larsson and Sues (2007):[7]
More recent studies have nested Baurusuchus deep within Notosuchia, just as the larger group Sebecosuchia once was, while the remaining sebecosuchian genera have been placed more distantly in Metasuchia.[20] A new baurusuchid called Pissarrachampsa was named in 2011, and a comprehensive phylogenetic analysis of baurusuchids was conducted along with its description. Montefeltro et al. (2011) found Baurusuchidae to be a monophyletic group with the genera Baurusuchus, Cynodontosuchus, Pissarrachampsa, Stratiotosuchus, and Wargosuchus. They adopted the name Baurusuchia in a phylogenetic sense to distinguish baurusuchids from related crocodyliforms. Baurusuchia was first erected as an infraorder in 1968, but in the 2011 analysis it was found to be in an identical position to Baurusuchidae in the final tree. The only difference between Baurusuchidae and Baurusuchia is that the former is a node-based taxon and the latter is a stem-based taxon. Baurusuchidae is defined as the least inclusive clade containing Cynodontosuchus rothi, Pissarrachampsa sera, and Baurusuchus pachecoi.[2] As in all node-based clades, there is a most recent common ancestor; these genera are all of its known descendants. Baurusuchia is formally defined as the most inclusive clade containing Baurusuchus pachecoi but not Sebecus icaeorhinus, Sphagesaurus huenei, Araripesuchus gomesi, Montealtosuchus arrudacamposi, or Crocodylus niloticus.[2]
In contrast to the node-based Baurusuchidae, the stem-based Baurusuchia does not include a common ancestor and all its descendants, but rather all forms more closely related to a specific baurusuchid than a non-baurusuchid. As a stem-based taxon, Baurusuchia is more inclusive than Baurusuchidae; a new taxon could potentially be placed outside Baurusuchidae because it is not a descendant of the most recent common ancestor of baurusuchids, but would still be a baurusuchian because it is more closely related to baurusuchids than it is to other crocodyliforms. For now, however, Baurusuchidae and Baurusuchia are almost identical in scope, with Baurusuchia also including Pabwehshi, based on their reference phylogenies.[12] Other analyses however, have recovered additional taxa within Baurusuchia outside of Baurusuchidae. (Pakasuchus and Comahuesuchus)[21]
Montefeltro et al. (2011) also divided Baurusuchidae into two subfamilies, Pissarrachampsinae and Baurusuchinae. Pissarrachampsinae includes Pissarrachampsa and Wargosuchus while Baurusuchinae includes Stratiotosuchus and Baurusuchus. Cynodontosuchus is not a member of either of these subfamilies, but the most basal baurusuchid. Many of the unique features that separate Cynodontosuchus may also be associated with a juvenile individual. The material that Cynodontosuchus is based on has been suggested to be a juvenile form of Wargosuchus, and the two taxa may be synonymous.[12]
Below is a cladogram from Montefeltro et al. (2011):[12]
A sixth genus of baurusuchid, Campinasuchus, was named just a few months before Pissarrachampsa, and was not included in the analysis.[22]
Darlim et al. (2021) described a new baurusuchid, Aphaurosuchus, and proposed formal definitions for the clades Baurusuchia, Baurusuchidae, Baurusuchinae, and Pissarrachampsinae. In addition to this, the study conducted a phylogenetic analysis to resolve the affinites of the new taxon and provide a reference phylogeny for the newly defined clades. The cladogram of this analysis is shown below.[2]
In 2011, fossilized eggs were described from the Late Cretaceous Adamantina Formation of Brazil that may have been laid by a baurusuchid, most probably Baurusuchus. A new oospecies called Bauruoolithus fragilis was named on the basis of these remains. The eggs are about twice as long as they are wide and have blunt ends. At about a quarter of a millimeter in thickness, the shells are relatively thin. Some eggs may have already hatched by the time they were buried, but none show extensive degradation. In living crocodilians (the closest living relatives of baurusuchids), eggs undergo extrinsic degradation to allow hatchlings to easily break through their shells. The fossils indicate that baurusuchid hatchlings probably broke through thin egg shells rather than shells that had been degraded over their incubation period.[23]
Related Research Articles
Baurusuchus is an extinct member of the ancestral crocodilian lineage, which lived in Brazil from 90 to 83.5 million years ago, in the Late Cretaceous period. Technically, it is a genus of baurusuchid mesoeucrocodylian. It was a terrestrial predator and scavenger, estimated to reach up to 113.4 kilograms (250 lb) in weight. Baurusuchus lived during the Turonian to Santonian stages of the Late Cretaceous Period, in Adamantina Formation, Brazil. It gets its name from the Brazilian Bauru Group. It was related to the earlier-named Cynodontosuchus rothi, which was smaller, with weaker dentition. The three species are B. pachechoi, named after Eng Joviano Pacheco, its discoverer, B. salgadoensis and B. albertoi. The latter species is disputed. Its relatives include the similarly sized Stratiotosuchus from the Adamantina Formation, and Pabweshi, from the Pakistani Pab Formation.
Notosuchia is a suborder of primarily Gondwanan mesoeucrocodylian crocodylomorphs that lived during the Jurassic and Cretaceous. Some phylogenies recover Sebecosuchia as a clade within Notosuchia, others as a sister group ; if Sebecosuchia is included within Notosuchia its existence is pushed into the Middle Miocene, about 11 million years ago. Fossils have been found from South America, Africa, Asia, and Europe. Notosuchia was a clade of terrestrial crocodilians that evolved a range of feeding behaviours, including herbivory (Chimaerasuchus), omnivory (Simosuchus), and terrestrial hypercarnivory (Baurusuchus). It included many members with highly derived traits unusual for crocodylomorphs, including mammal-like teeth, flexible bands of shield-like body armor similar to those of armadillos (Armadillosuchus), and possibly fleshy cheeks and pig-like snouts (Notosuchus). The suborder was first named in 1971 by Zulma Gasparini and has since undergone many phylogenetic revisions.
The Adamantina Formation is a geological formation in the Bauru Basin of western São Paulo state, in southeastern Brazil.
Pabwehshi is an extinct genus of mesoeucrocodylian. It is based on GSP-UM 2000, a partial snout and corresponding lower jaw elements, with another snout assigned to it. These specimens were found in Maastrichtian-age Upper Cretaceous rocks of the Vitakri and Pab Formations in Balochistan, Pakistan, and represent the first diagnostic crocodyliform fossils from Cretaceous rocks of South Asia. Pabwehshi had serrated interlocking teeth in its snout that formed a "zig-zag" cutting edge. Pabwehshi was named in 2001 by Jeffrey A. Wilson and colleagues. The type species is P. pakistanensis, in reference to the nation where it was found. It was traditionally classified as a baurusuchid closely related to Cynodontosuchus and Baurusuchus. Larsson and Sues (2007) found close affinity between Pabwehshi and the Peirosauridae within Sebecia. Montefeltro et al.Pabwehshi has a sagittal torus on its maxillary palatal shelves – a character that is absent in baurusuchids – but they did not include Pabwehshi in their phylogenetic analysis.
Trematochampsidae is an extinct family of mesoeucrocodylian crocodylomorphs. Fossils are present from Madagascar, Morocco, Niger, Argentina, and Brazil. Possible trematochampsids have been found from Spain and France, but classification past the family level is indeterminant. The trematochampsids first appeared during the Barremian stage of the Early Cretaceous and became extinct during the late Maastrichtian stage of the Late Cretaceous.
Bergisuchus is an extinct genus of small sebecosuchian mesoeucrocodylian known primarily from the Eocene Messel Pit in Germany. Few fossils of Bergisuchus have been discovered, only a single incomplete snout, a few partial lower jaws and some teeth. Despite being fragmentary, the jaw bones are enough to indicate that Bergisuchus had a short, deep, narrow snout and serrated teeth, quite unlike the broad flat snouts of modern crocodylians.
Neosuchia is a clade within Mesoeucrocodylia that includes all modern extant crocodilians and their closest fossil relatives. It is defined as the most inclusive clade containing all crocodylomorphs more closely related to Crocodylus niloticus than to Notosuchus terrestris. Members of Neosuchia generally share a crocodilian-like bodyform adapted to freshwater aquatic life, as opposed to the terrestrial habits of more basal crocodylomorph groups. The earliest neosuchian is suggested to be the Early Jurassic Calsoyasuchus, which lived during the Sinemurian and Pliensbachian stages in North America. It is often identified as a member of Goniopholididae, though this is disputed, and the taxon may lie outside Neosuchia, which places the earliest records of the group in the Middle Jurassic.
Eremosuchus is an extinct genus of sebecosuchian mesoeucrocodylian. Fossils have been found from El Kohol, Algeria of Eocene age. It had serrated, ziphodont teeth.
Ilchunaia is an extinct genus of sebecid mesoeucrocodylian. Fossils have been found from the Divisadero Largo Formation of Argentina dating back to the Late Eocene, and a locality in Mendoza, Argentina dating back to the Oligocene. Little material is known from the genus, with only the anterior portion of the skull being present to study.
Metasuchia is a major clade within the superorder Crocodylomorpha. It is split into two main groups, Ziphosuchia and Neosuchia. Notosuchia is an extinct group that contains primarily small-bodied Cretaceous taxa with heterodont dentition. Neosuchia includes the extant crocodylians and basal taxa, such as peirosaurids and pholidosaurids. It is phylogenetically defined by Sereno et al. (2001) as a clade containing Notosuchus terrestris, Crocodylus niloticus, and all descendants of their common ancestor.
Sebecus is an extinct genus of sebecid crocodylomorph from Eocene of South America. Like other sebecosuchians, it was entirely terrestrial and carnivorous. The genus is currently represented by two species, the type S. icaeorhinus and S. ayrampu. Several other species have been referred to Sebecus, but were later reclassified as their own genera.
Sebecia is an extinct clade of mesoeucrocodylian crocodyliforms that includes peirosaurids and sebecids. It was first constructed in 2007 to include Hamadasuchus, Peirosauridae, and Sebecus. It was initially considered to be the sister taxon of the clade Neosuchia, which includes living crocodilians, although some later studies have placed it within Neosuchia as a basal clade. Sebecians were terrestrial crocodyliforms characterized by their deep snouts and ziphodont dentition. They first appeared in the Late Cretaceous, survived the Cretaceous–Paleogene extinction event, and became extinct in the Miocene epoch.
Sebecosuchia is an extinct group of mesoeucrocodylian crocodyliforms that includes the families Sebecidae and Baurusuchidae. The group was long thought to have first appeared in the Late Cretaceous with the baurusuchids and become extinct in the Miocene with the last sebecids, but Razanandrongobe pushes the origin of Sebecosuchia to the Middle Jurassic. Fossils have been found primarily from South America but have also been found in Europe, North Africa, Madagascar, and the Indian subcontinent.
Ziphosuchia is a clade of mesoeucrocodylian crocodyliforms that includes notosuchians and sebecosuchians.
Stratiotosuchus is an extinct genus of baurusuchid mesoeucrocodylian from the Adamantina Formation in Brazil. It lived during the Late Cretaceous. The first fossils were found in the 1980s, and the type species Stratiotosuchus maxhechti was named in 2001. A hyperpredator, it and other baurusuchids may have filled niches occupied elsewhere by theropod dinosaurs.
Pissarrachampsa is an extinct genus of baurusuchid mesoeucrocodylian from the Late Cretaceous of Brazil. It is based on a nearly complete skull and a referred partial skull and lower jaw from the ?Campanian - ?Maastrichtian-age Vale do Rio do Peixe Formation of the Bauru Group, found in the vicinity of Gurinhatã, Brazil.
Pissarrachampsinae is a subfamily of baurusuchid crocodyliforms from the Late Cretaceous of Brazil and Argentina. It was named in 2011 with the description of Pissarrachampsa sera and includes P. sera from Brazil and the related Wargosuchus australis from Argentina. Pissarrachampsinae is one of two subfamilies of Baurusuchidae, the other being Baurusuchinae.
Baurusuchinae is a subfamily of baurusuchid crocodyliforms from the Late Cretaceous of Brazil. Named in 2011, it contains the baurusuchids Aphaurosuchus, Aplestosuchus, Baurusuchus and Stratiotosuchus. Baurusuchinae is one of two subfamilies of Baurusuchidae, the other being Pissarrachampsinae.
Aplestosuchus is an extinct genus of baurusuchid mesoeucrocodylian known from the Late Cretaceous Adamantina Formation of São Paulo, southern Brazil. It contains a single species, Aplestosuchus sordidus. A. sordidus is represented by a single articulated and nearly complete skeleton, preserving the remains of an unidentified sphagesaurid crocodyliform in its abdominal cavity. The specimen represents direct evidence of predation between different taxa of crocodyliforms in the fossil record.
Aphaurosuchus is an extinct genus of baurusuchid mesoeucrocodylian known from the Late Cretaceous Bauru Basin of São Paulo, southern Brazil. It contains two species, Aphaurosuchus escharafacies and Aphaurosuchus kaiju.
↑ Woodward, A.S. (1896). ". On two Mesozoic crocodilians, Notosuchus (genus novum) and Cynodontosuchus (genus novum) from the red sandstones of the Territory of Neuquén (Argentine Republic)". Anales del Museo de la Plata (Paleontología). 4: 1–20.
↑ Martinelli, A.G.; Pais, D.F. (2008). "A new baurusuchid crocodyliform (Archosauria) from the Late Cretaceous of Patagonia (Argentina)". Comptes Rendus Palevol. 7 (6): 371–381. Bibcode:2008CRPal...7..371M. doi:10.1016/j.crpv.2008.05.002.
↑ Wilson, J.A.; Malkane, M.S.; Gingerich, P.D. (2001). "New crocodyliform (Reptilia, Mesoeucrocodylia) from the Upper Cretaceous Pab Formation of Vitakri, Balochistan (Pakistan)". Contributions from the Museum of Paleontology, University of Michigan. 30 (12): 321–336.
↑ Price, L.I. (1945). "A new reptile from the Cretaceous of Brazil". Rio de Janeiro, Departamento Nacional da Produção Mineral, Notas preliminares e estudos. 25: 1–8.
↑ Colbert, E.H. (1946). "Sebecus, representative of a peculiar suborder of fossil Crocodilia from Patagonia". Bulletin of the American Museum of Natural History. 87: 217–270.
↑ Gasparini, Z.B.; Chiappe, L.M.; Fernandez, M. (1991). "A new Senonian peirosaurid (Crocodylomorpha) from Argentina and a sinopsis of the South American Cretaceous crocodilians". Journal of Vertebrate Paleontology. 11 (3): 316–333. Bibcode:1991JVPal..11..316G. doi:10.1080/02724634.1991.10011401.
↑ Ortega, F.; Buscaloni, A.D; Gasaparini, Z. (1996). "Reinterpretation and new denomination of Atacisaurus crassiproratus (Middle Eocene; Issel, France) as cf. Iberosuchus (Crocodylomorpha, Metasuchia)". Geobios. 29 (3): 353–364. Bibcode:1996Geobi..29..353O. doi:10.1016/S0016-6995(96)80037-4.
↑ Ortega, F. Z.; Buscalioni, A. D.; Calvo, J. O. (2000). "A new species of Araripesuchus (Crocodylomorpha, Mesoeucrocodylia) from the Lower Cretaceous of Patagonia (Argentina)". Journal of Vertebrate Paleontology. 20 (1): 57–76. doi:10.1671/0272-4634(2000)020[0057:ANSOAC]2.0.CO;2. S2CID85946263.
↑ Clark, J.M. (1997). "Patterns of evolution in Mesozoic Crocodyliformes". In Fraser, N.C.; Sues, H.-D. (eds.). In the Shadow of the Dinosaurs: Early Mesozoic Tetrapods. Cambridge: Cambridge University Press. pp.84–97.
↑ Pol, D. (1999). "Basal Mesoeucrocodylian relationships: new clues to old conflicts". Journal of Vertebrate Paleontology. 19 (3, Supplement): 69A. doi:10.1080/02724634.1999.10011202.
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