Crocodyliformes

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Crocodyliformes
Temporal range: Late Triassic Recent, 225–0  Ma
Protosuchus BW.jpg
Protosuchus , an early crocodyliform
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauria
Clade: Pseudosuchia
Clade: Crocodylomorpha
Clade: Solidocrania
Clade: Crocodyliformes
Hay, 1930
Clades

Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the only pseudosuchians to survive the K-Pg extinction event.

Contents

In 1988, James M. Clark argued that traditional names for well-known groups of animals should be restricted to their crown clades, that is, used only for natural groups comprising all living members of any given lineage and descendants of their closest common ancestor. This posed a problem for the crocodilians, because the name Crocodylia, while used in various ways by various scientists, had always included not only living crocodilians but many of their extinct ancestors known only from the fossil record. [1]

Clark's solution to this issue was to restrict the name Crocodylia to the group containing modern alligators, crocodiles, and gharials, plus any extinct taxa descended from their closest common ancestor. The traditional group "Crocodylia" was replaced by the name Crocodyliformes, defined to include many of the extinct families that the new definition left out. Clark did not initially provide an exact definition for Crocodyliformes; but, in 2001, Paul Sereno and colleagues defined it as the clade including Protosuchus richardsoni and the Nile crocodile, plus all descendants of their common ancestor. [2]

Christopher Brochu agreed with the assessment that Crocodylia as a name has never had stable contents, and that a series of clades larger than the crown group Crocodylia (including Crocodyliformes and the slightly more inclusive clade Crocodylomorpha) was a good solution. [3] However, in a 2008 paper, Jeremy Martin and Benton reversed the previous opinion (co-authored by Benton) that Crocodylia should be restricted to the crown group, suggesting that Crocodyliformes should be considered a synonym of a more inclusive Crocodylia, and thus replaced. [4] Brochu and colleagues rejected this proposal, arguing that the crown definition of Crocodylia is the standard meaning both within and beyond the crocodyliform systematics community. [5]

Ecology

While all extant crocodilians are carnivorous, the ecological roles of Mesozoic crocodyliforms were more diverse, and included omnivory and herbivory. Herbivorous forms were present from the early Jurassic to the late Cretaceous and are thought to have evolved at least three times. [6]

Fossil tracks

Tracks of a crocodyliform are known since Cretaceous, at least. Tracks representing the ichnofamily Batrachopodidae are described from the Early Cretaceous (late Aptian) Calonda Formation (Angola) by Mateus et al. (2017), who name a new ichnotaxon Angolaichnus adamanticus. [7]

Phylogeny

Below is a simplified cladogram based on Fiorelli and Calvo (2007). [8]

Crocodylomorpha

In 2012, paleontologists Mario Bronzati, Felipe Chinaglia Montefeltro, and Max C. Langer conducted a broad phylogenetic analysis to produce supertrees of Crocodyliformes, including 184 species. The most parsimonious trees were highly resolved, meaning the phylogenetic relationships found in the analysis were highly likely. Below is a consensus tree based off the study: [9]

Kayentasuchus walkeri

Crocodyliformes
Protosuchia
Gobiosuchidae

Eopneumatosuchus colberti

Notosuchia

Related Research Articles

<span class="mw-page-title-main">Archosaur</span> Group of diapsids broadly classified as reptiles

Archosauria or archosaurs is a clade of diapsid sauropsid tetrapods, with birds and crocodilians being the only extant representatives. Although broadly classified as reptiles, which traditionally exclude birds, the cladistic sense of the term includes all living and extinct relatives of birds and crocodilians such as non-avian dinosaurs, pterosaurs, phytosaurs, aetosaurs and rauisuchians as well as many Mesozoic marine reptiles. Modern paleontologists define Archosauria as a crown group that includes the most recent common ancestor of living birds and crocodilians, and all of its descendants.

<span class="mw-page-title-main">Crurotarsi</span> Clade of reptiles

Crurotarsi is a clade of archosauriform reptiles that includes crocodilians and stem-crocodilians and possibly bird-line archosaurs too if the extinct, crocodile-like phytosaurs are more distantly related to crocodiles than traditionally thought. Prior to 2011, the group had invariably included only archosaurs closer to crocodilians than to birds and other dinosaurs. An equivalent term for the crocodilian side of the archosaur family tree is Pseudosuchia. This traditional definition of Crurotarsi assumed that phytosaurs were crown-group archosaurs and more closely related to crocodilians than to birds. However, a 2011 study argued that the phytosaur lineage evolved prior to the split between birds and crocodilians. This would mean that phytosaurs were not true archosaurs, and therefore could not be considered representatives of croc-line archosaurs.

<span class="mw-page-title-main">Pseudosuchia</span> Clade of reptiles

Pseudosuchia is one of two major divisions of Archosauria, including living crocodilians and all archosaurs more closely related to crocodilians than to birds. Pseudosuchians are also informally known as "crocodilian-line archosaurs". Despite Pseudosuchia meaning "false crocodiles", the name is a misnomer as true crocodilians are now defined as a subset of the group.

<span class="mw-page-title-main">Mesoeucrocodylia</span> Clade of reptiles

Mesoeucrocodylia is the clade that includes Eusuchia and crocodyliforms formerly placed in the paraphyletic group Mesosuchia. The group appeared during the Early Jurassic, and continues to the present day.

<i>Terrestrisuchus</i> Genus of terrestrial crocodylomorph

Terrestrisuchus is an extinct genus of very small early crocodylomorph that was about 76 centimetres (30 in) long. Fossils have been found in Wales and Southern England and date from near the very end of the Late Triassic during the Rhaetian, and it is known by type and only known species T. gracilis. Terrestrisuchus was a long-legged, active predator that lived entirely on land, unlike modern crocodilians. It inhabited a chain of tropical, low-lying islands that made up southern Britain, along with similarly small-sized dinosaurs and abundant rhynchocephalians. Numerous fossils of Terrestrisuchus are known from fissures in limestone karst which made up the islands it lived on, which formed caverns and sinkholes that preserved the remains of Terrestrisuchus and other island-living reptiles.

<span class="mw-page-title-main">Avemetatarsalia</span> Clade of archosaur reptiles

Avemetatarsalia is a clade of diapsid reptiles containing all archosaurs more closely related to birds than to crocodilians. The two most successful groups of avemetatarsalians were the dinosaurs and pterosaurs. Dinosaurs were the largest terrestrial animals for much of the Mesozoic Era, and one group of small feathered dinosaurs has survived up to the present day. Pterosaurs were the first flying vertebrates and persisted through the Mesozoic before dying out at the Cretaceous-Paleogene (K-Pg) extinction event. Both dinosaurs and pterosaurs appeared in the Triassic Period, shortly after avemetatarsalians as a whole. The name Avemetatarsalia was first established by British palaeontologist Michael Benton in 1999. An alternate name is Pan-Aves, or "all birds", in reference to its definition containing all animals, living or extinct, which are more closely related to birds than to crocodilians.

<span class="mw-page-title-main">Crocodylomorpha</span> Clade of reptiles

Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. Extinct crocodylomorphs were considerably more ecologically diverse than modern crocodillians. The earliest and most primitive crocodylomorphs are represented by "sphenosuchians", a paraphyletic assemblage containing small-bodied, slender forms with elongated limbs that walked upright, which represents the ancestral morphology of Crocodylomorpha. These forms persisted until the end of the Jurassic. During the Jurassic, crocodylomorphs morphologically diversified into numerous niches, with the subgroups Neosuchia and the extinct Thalattosuchia adapting to aquatic life, while some terrestrial groups adopted herbivorous and omnivorous lifestyles. Terrestrial crocodylomorphs would continue to co-exist alongside aquatic forms until becoming extinct during the Miocene.

Elosuchus is an extinct genus of neosuchian crocodyliform that lived during the Middle Cretaceous of what is now Africa.

<i>Pelagosaurus</i> Extinct genus of reptiles

Pelagosaurus is an extinct genus of thalattosuchian crocodyliform that lived during the Toarcian stage of the Lower Jurassic, around 183 Ma to 176 Ma, in shallow epicontinental seas that covered much of what is now Western Europe. The systematic taxonomy of Pelagosaurus has been fiercely disputed over the years, and was assigned to Thalattosuchia after its systematics within Teleosauridae were disputed. Pelagosaurus measured 2–3 m (6.6–9.8 ft) long.

<span class="mw-page-title-main">Notosuchia</span> Extinct suborder of reptiles

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.

<span class="mw-page-title-main">Baurusuchidae</span> Extinct family of reptiles

Baurusuchidae is a Gondwanan family of mesoeucrocodylians that lived during the Late Cretaceous. It is a group of terrestrial hypercarnivorous crocodilians from South America and possibly Pakistan. Baurusuchidae has been, in accordance with the PhyloCode, officially defined as the least inclusive clade containing Cynodontosuchus rothi, Pissarrachampsa sera, and Baurusuchus pachecoi. Baurusuchids have been placed in the suborder Baurusuchia, and two subfamilies have been proposed: Baurusuchinae and Pissarrachampsinae.

<span class="mw-page-title-main">Eusuchia</span> Clade of reptiles

Eusuchia is a clade of neosuchian crocodylomorphs that first appeared in the Early Cretaceous, which includes modern crocodilians. Along with Dyrosauridae and Sebecosuchia, they were the only crocodyliformes who survived the K-Pg extinction.

Trematochampsidae is an extinct family of mesoeucrocodylian crocodyliforms. 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.

<span class="mw-page-title-main">Neosuchia</span> Clade of reptiles

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.

Stolokrosuchus is an extinct genus of crocodyliforms that lived during the Early Cretaceous. Its fossils, including a skull with a long thin snout and bony knobs on the prefrontal, have been found in Niger. Stolokrosuchus was described in 2000 by Hans Larsson and Boubacar Gado. The type species is S. lapparenti. They initially described it as related to Peirosauridae, if not a member of that family. One study has shown it to be related to Elosuchus. However, more recent works usually find Stolokrosuchus to be one of the basalmost neosuchian, only distantly related to the elosuchid or pholidosaurid, Elosuchus. It was a semiaquatic crocodylomorph.

<span class="mw-page-title-main">Metasuchia</span> Clade of reptiles

Metasuchia is a major clade within the superorder Crocodylomorpha. It is split into two main groups, Notosuchia 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.

<i>Pholidosaurus</i> Extinct genus of reptiles

Pholidosaurus is an extinct genus of neosuchian crocodylomorph. It is the type genus of the family Pholidosauridae. Fossils have been found in northwestern Germany. The genus is known to have existed during the Berriasian-Albian stages of the Early Cretaceous. Fossil material found from the Annero and Jydegård Formations in Skåne, Sweden and on the island of Bornholm, Denmark, have been referred to as a mesoeucrocodylian, and possibly represent the genus Pholidosaurus.

Shartegosuchidae is an extinct family of Late Jurassic and Early Cretaceous crocodyliforms. The family is named after the Late Jurassic Shar Teeg Beds in southwestern Mongolia, from which most shartegosuchid remains have been found. Five genera are currently assigned to Shartegosuchidae: Shartegosuchus, Nominosuchus, Kyasuchus, Adzhosuchus, and Fruitachampsa. Shartegosuchus, Nominosuchus, and Adzhosuchus all come from Shar Teeg, while Kyasuchus is known from the Early Cretaceous of Russia. Fruitachampsa is known from the Late Jurassic Morrison Formation of the western United States.

<span class="mw-page-title-main">Suchia</span> Clade of reptiles

Suchia is a clade of archosaurs containing the majority of pseudosuchians. It was defined as the least inclusive clade containing Aetosaurus ferratus, Rauisuchus tiradentes, Prestosuchus chiniquensis, and Crocodylus niloticus by Nesbitt (2011). Generally the only pseudosuchian group which is omitted from Suchia is the family Ornithosuchidae, although at least one analysis classifies ornithosuchids as close relatives of erpetosuchids and aetosaurs. Phytosaurs are also excluded from Suchia, although it is not certain whether they qualify as pseudosuchians in the first place.

<span class="mw-page-title-main">Brevirostres</span> Taxon of reptiles

Brevirostres is a paraphyletic group of crocodilians that included alligatoroids and crocodyloids. Brevirostres are crocodilians with small snouts, and are distinguished from the long-snouted gharials. It is defined phylogenetically as the last common ancestor of Alligator mississippiensis and Crocodylus niloticus and all of its descendants. This classification was based on morphological studies primarily focused on analyzing skeletal traits of living and extinct fossil species, and placed the gharials outside the group due to their unique skull structure, and can be shown in the simplified cladogram below:

References

  1. Benton, M.J. and Clark, J.M. (1988). "Archosaur phylogeny and the relationships of the Crocodylia." Pp. 295–338 in Benton, M.J. (ed.), The phylogeny and classification of the Tetrapods, volume 1. Oxford: Clarendon Press.
  2. Sereno, P.C.; Larson, H.C.E.; Sidor, C.A.; Gado, B. (2001). "The giant crocodyliform Sarcosuchus from the Cretaceous of Africa" (PDF). Science. 294 (5546): 1516–1519. Bibcode:2001Sci...294.1516S. doi:10.1126/science.1066521. PMID   11679634. S2CID   22956704.
  3. Brochu, C.A. (2003). "Phylogenetic approaches toward crocodylian history". Annu. Rev. Earth Planet. Sci. 31 (31): 357–397. Bibcode:2003AREPS..31..357B. doi:10.1146/annurev.earth.31.100901.141308.
  4. Martin, J.E.; Benton, M.J. (2008). "Crown Clades in Vertebrate Nomenclature: Correcting the Definition of Crocodylia". Systematic Biology. 57 (1): 173–181. doi: 10.1080/10635150801910469 . PMID   18300130.
  5. Brochu, A.C.; Wagner, J.R.; Jouve, S.; Sumrall, C.D.; Densmore, L.D. (2009). "A correction corrected: consensus over the meaning of Crocodylia and why it matters". Systematic Biology. 58 (5): 537–543. doi:10.1093/sysbio/syp053. PMID   20525607.
  6. Melstrom, K. M.; Irmis, R. B. (2019). "Repeated Evolution of Herbivorous Crocodyliforms during the Age of Dinosaurs". Current Biology. 29 (14): 2389–2395.e3. doi: 10.1016/j.cub.2019.05.076 . PMID   31257139.
  7. Octávio Mateus; Marco Marzola; Anne S. Schulp; Louis L. Jacobs; Michael J. Polcyn; Vladimir Pervov; António Olímpio Gonçalves; Maria Luisa Morais (2017). "Angolan ichnosite in a diamond mine shows the presence of a large terrestrial mammaliamorph, a crocodylomorph, and sauropod dinosaurs in the Early Cretaceous of Africa". Palaeogeography, Palaeoclimatology, Palaeoecology. 471: 220–232. Bibcode:2017PPP...471..220M. doi:10.1016/j.palaeo.2016.12.049.
  8. Fiorelli, LE; Calvo, JO (2007). "The first "protosuchian" (Archosauria: Crocodyliformes) from the Cretaceous (Santonian) of Gondwana". Arquivos do Museu Nacional, Rio de Janeiro. 65 (4): 417–459.
  9. Bronzati, M.; Montefeltro, F. C.; Langer, M. C. (2012). "A species-level supertree of Crocodyliformes". Historical Biology. 24 (6): 598–606. doi:10.1080/08912963.2012.662680. S2CID   53412111.