Sphenosuchia

Sphenosuchia
Temporal range: Late Triassic - Late Jurassic, 228–152 Ma
Hesperosuchus BW.jpg
Life restoration of Hesperosuchus agilis
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Pseudosuchia
Superorder: Crocodylomorpha
Informal group: Sphenosuchia
von Huene, 1942
Genera

See below

Synonyms
  • Pedeticosauria Walker, 1968

Sphenosuchia is a suborder of basal crocodylomorphs that first appeared in the Triassic and occurred into the Middle Jurassic. Most were small, gracile animals with an erect limb posture. They are now thought to be ancestral to crocodyliforms, a group which includes all living crocodilians.

Stratigraphic range

The earliest known members of the group (i.e. Hesperosuchus) are early Norian in age, found in the Blue Mesa Member of the Chinle Formation. Only one sphenosuchian is currently known from the Middle Jurassic, Junggarsuchus, from the Junggar Basin (Shishugou Formation) of China during either the Bathonian or the Callovian (~165 Ma) age, and the Hallopodidae are known from the Late Jurassic of North America.

Phylogeny

The monophyly of the group is debated, although several synapomorphies characterize the clade, including extremely slender limbs, a compact carpus and an elongate coracoid process.

In 2002, Clark and Sues found a possible sphenosuchian clade of Dibothrosuchus, Sphenosuchus, and possibly Hesperosuchus and Saltoposuchus, with several other genera in unresolved positions (Kayentasuchus, Litargosuchus, Pseudhesperosuchus, and Terrestrisuchus). More recently, however, Clark et al. (2004) argued for the paraphyly of the group, contending that morphological characters were secondarily lost in more highly derived crocodylomorphs. Further analysis and study is required before the group's monophyly is resolved with certainty — a perfect phylogenetic analysis is, at present, impossible due to a paucity of fossil remains demonstrating phylogenetically informative characters.

Below is a cladogram modified from Nesbitt (2011). Sphenosuchians are marked by the green bracket.

Crocodylomorpha 

CM 73372

Hesperosuchus

Dromicosuchus

Sphenosuchus

Dibothrosuchus

Terrestrisuchus

Litargosuchus

Kayentasuchus

 Crocodyliformes 

Orthosuchus

Protosuchus

Alligator

Sphenosuchians

Genera

Genus Status Age Location Unit Notes Images
Valid Early Jurassic  China Lower Lufeng Series Dibothrosuchus BW.jpg
Valid Late Triassic  USA Newark Supergroup
Valid Late Triassic (Carnian)  Germany Schilfsandstein Formation A possible sphenosuchian; alternatively, it could be an erpetosuchid. Dyoplax holotype.jpg
Valid Late Triassic (Carnian)  USA Chinle Formation
Valid Middle Jurassic  China Shishugou Formation Junggarsuchus sloani.jpg
Valid Early Jurassic (Sinemurian - Pliensbachian)  USA Kayenta Formation
Valid Early Jurassic  South Africa Elliot Formation Litargosuchus leptorhynchus.jpg
Nomen dubium Late Triassic  USA Dockum Group An indeterminate sphenosuchian known only from undiagnostic vertebrae
Valid Early Jurassic  China Lower Lufeng Series
Valid Late Triassic (Norian)  Argentina Los Colorados Formation
Valid Late Triassic  USA Redonda Formation
Valid Late Triassic (Norian)  Germany

 Switzerland  UK

Löwenstein Formation

Trossingen Formation Lossiemouth Sandstone

Saltoposuchus BW.jpg
Valid Early Jurassic  South Africa Elliot Formation
Valid. Late Triassic  UK Terrestrisuchus BW.jpg
Valid Late Triassic  Argentina Ischigualasto Formation

This page was last updated at 2023-04-24 11:30 UTC. Update now. View original page.

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