Crocodylomorpha

'' from the Late Triassic (Carnian) of North America, an early branching, so-called "sphenosuchian" crocodylomorph|330x330px ''. The earliest lineages of Crocodylomorpha are placed into the paraphyletic "Sphenosuchia", which are characterized by slender bodies with elongate legs. The oldest known crocodylomorph is Trialestes, known from the Late Triassic (Carnian-Norian) of Argentina, around 231–225 million years ago, the last groups of "sphenosuchians" persisted until the end of the Jurassic. as well as the aquatically adapted Neosuchia and Thalattosuchia, with Thalattosuchia and several groups of neosuchians becoming adapted to a marine lifestyle over the Jurassic and Cretaceous During the Cretaceous, the Notosuchia were a diverse group across the Southern Hemisphere occupying many diverse ecologies. Modern crocodilians, a subgroup of Neosuchia, emerged during the Late Cretaceous. ==Taxonomy and phylogeny==

Historically, all known living and extinct crocodiles were indiscriminately lumped into the order Crocodilia. However, beginning in the late 1980s, many scientists began restricting the order Crocodilia to the living species and close extinct relatives such as Mekosuchus. The various other groups that had previously been known as Crocodilia were moved to Crocodylomorpha and the slightly more restrictive Crocodyliformes. Crocodylomorpha has been given the rank of superorder in some 20th and 21st century studies. The old Crocodilia was subdivided into the suborders: • Eusuchia: true crocodiles (which includes crown-group Crocodylia) • Mesosuchia: 'middle' crocodiles • Thalattosuchia: sea crocodiles • Protosuchia: first crocodiles • Sphenosuchia: wedge crocodiles • Sebecosuchia: Sebecus crocodiles Mesosuchia is a paraphyletic group as it does not include eusuchians (which nest within Mesosuchia). Mesoeucrocodylia was the name given to the clade that contains mesosuchians and eusuchians (Whetstone and Whybrow, 1983). The previous definitions of Crocodilia and Eusuchia did not accurately convey evolutionary relationships within the group. The only order-level taxon that is currently considered valid is Crocodilia in its present definition. Prehistoric crocodiles are represented by many taxa, but since few major groups of the ancient forms are distinguishable, a conclusion on how to define new order-level clades is not yet possible. (Benson & Clark, 1988). Crocodylomorpha in the modern sense, as defined by Paul Sereno in 2005, is phylogenetically defined as the most inclusive clade containing Crocodylus niloticus (the Nile crocodile), but not Rauisuchus tiradentes, Poposaurus gracilis, Gracilisuchus stipanicicorum, Prestosuchus chiniquensis, or Aetosaurus ferratus. Phylogeny Below is a cladogram of most known crocodylomorphs from Stephan F. Speikeman in 2023. The following cladogram was published by Juan Martín Leardi in 2025. }} }} }} }} }} }} }} }}Cladogram from Bodenham et al. 2026:|style=}} ==Biology==

The Crocodylomorpha comprise a variety of forms, shapes, and sizes, which occupied a range of habitats. As with most amniotes, Crocodylomorphs were and are oviparous, laying eggs in a nest or mound, known from strata as old as the Late Jurassic. Adult size varies widely, from about 55 cm long in Knoetschkesuchus to much larger dimensions, as in Sarcosuchus. Most crocodylomorphs were carnivores, but many lineages evolved to be obligate piscivores, such as the extant gharials. In some forms, like Hesperosuchus and Terrestrisuchus, metatarsal V still had one or two phalanges, but in Crocodyliformes all metatarsal V phalanges have been lost. ==References==