Calyptosuchus

{{short description|Extinct genus of reptiles}} {{Automatic taxobox | fossil_range = [[Late Triassic]], mid [[Norian]], ~{{fossil_range|219}} | taxon = Calyptosuchus | authority = Long & Ballew, 1985 | type_species = {{extinct}}'''''Calyptosuchus wellesi''''' | type_species_authority = Long & Ballew ,1985 }} '''''Calyptosuchus''''' (meaning "covered crocodile") is an [[extinct]] [[genus]] of [[aetosaur]] from the Late [[Triassic]] of [[North America]]. Like other aetosaurs, it was heavily armored and had a [[pig]]-like snout used to uproot [[plant]]s.<ref name=":0">{{Cite journal|last=Parker|first=William G.|date=2018-02-02|title=Redescription of ''Calyptosuchus (Stagonolepis) wellesi'' (Archosauria: Pseudosuchia: Aetosauria) from the Late Triassic of the Southwestern United States with a discussion of genera in vertebrate paleontology|journal=PeerJ|language=en|volume=6|article-number=e4291|doi=10.7717/peerj.4291|pmid=29416953|pmc=5798403|issn=2167-8359|doi-access=free}}</ref>

== Description == ''Calyptosuchus'' was estimated to have been four metres long, or possibly larger, with a maximum carapace width of almost seventy centimetres. The [[osteoderm]]s were not entirely fused. Each row of the osteoderms corresponded to one [[vertebra]], and comprised four dorsal osteoderms. Two small squarish osteoderms formed the outside of the row (about 10 by 10 cm), and two much broader osteoderms (approximately 20 by 10 cm) formed the inside of the row and covered most of the back. Each of the lateral osteoderms have a raised boss towards the centre at the posterior end of the osteoderm, and are almost bent around the side of the creature, with a dorsal flange along the back contacting the paramedian (dorsal) osteoderms and a lateral flange running a little way down the side. This would probably have given it quite a boxy look. The paramedian osteoderms also have a raised boss, called a dorsal eminence, in the posterior centre of the osteoderm but do not bend around in the same manner. There are ventral osteoderms known, but they have not been preserved in the natural alignment as the dorsal and lateral osteoderms have and so we are uncertain how they were arranged. They appear to have been flat and rectangular.<ref name=":0" />

The only [[skull]] fragment that is certainly ''Calyptosuchus'' is a [[Mandible|dentary bone]] - no other cranial bones have been assigned to it with certainty. Only a middle part of the dentary is present, with an [[Edentulism|edentulous]] patch to the anterior and nine [[Dental alveolus|dental alveoli]] posteriorly. No [[Tooth|teeth]] are preserved except a few fragments of root. A [[maxilla]] assigned with partial certainty to ''Calyptosuchus'' has five dental alveoli, and probably contacted the external [[Nostril|naris]] at a point.<ref name=":0" />

The vertebrae have keels, unusually among aetosaurs, and the [[Axis (anatomy)|axis vertebra]] has a noticeable concavity in the sides above which the [[zygapophyses]] protrude. Most of these are broken. The centrum of the axis is slightly wider than it is tall, but those of the other [[cervical vertebrae]] are taller than they are wide. [[Neural spines]] and arches are elongated in all the vertebrae along the trunk, and their centra have a concave anterior face and a flat posterior face. They are [[wikt:spool|spool]]-shaped, typically for aetosaur vertebrae. Their [[neural canal]]s are large and deep. The [[Sacrum|sacral vertebrae]] are very robust, and not fused unlike those of desmatosuchians. There are only two sacral vertebrae. The [[caudal vertebrae]] number at least seventeen, with very tall neural spines (taller than the centrum is) and low-attached caudal ribs. The [[holotype]] had all seventeen of the first caudal vertebrae articulated.<ref name=":0" />

Several [[Pelvis|pelvic girdles]] are known, with ventral [[Acetabulum|acetabula]] and thickened peduncles. The [[Iliac crest|iliac blades]] are short, but very broad. The [[Ischium|ischia]] are short and quite curved, with thickened areas and rugosities near the ends. Much of the [[Pubis (bone)|pubis]] is slender, but the distal end expands until it is quite broad. The [[femur]] is gracile, or more so than ''[[Desmatosuchus]]'', and has a pronounced crescent-shaped ridge near the proximal end. In a similar fashion, the [[tibia]] is also quite gracile and shorter than the femur. The distal end bears a deep groove for articulation with the ankle bones.<ref name=":0" />

==Classification== ''Calyptosuchus'' was named by Long and Ballew (1985) on the basis of UMMP 13950, a partial carapace with a vertebral column and pelvis that had been discovered in the [[Tecovas Formation]] of western Texas in 1931 by [[Ermin Cowles Case]], who only went as far to assign the specimen to [[Phytosauria]] in a 1932 paper.<ref>Case EC. 1932. A perfectly preserved segment of the armor of a phytosaur, with associated vertebrae. Contributions from the Museum of Paleontology. University of Michigan 4:57-80.</ref><ref>Long RA, Ballew KL. 1985. Aetosaur dermal armor from the late Triassic of southwestern North America, with special reference to material from the Chinle Formation of Petrified Forest National Park.</ref> Although publications in the 1990s and early 2000s treated the genus as a junior synonym of ''[[Stagonolepis]]'',<ref>Heckert AB, Lucas SG. 2000. Taxonomy, phylogeny, biostratigraphy, biochronology, paleobiogeography, and evolution of the Late Triassic Aetosauria (Archosauria: Crurotarsi) Zentralblatt für Geologie und Paläontologie Teil I 1998 Heft 11–12:1539-1587</ref><ref>Long RA, Murry PA. 1995. Late Triassic (Carnian and Norian) tetrapods from the southwestern United States. New Mexico Museum of Natural History and Science Bulletin 4:1-254</ref> recent work has found it generically distinct from ''Stagonolepis'' proper. This is because more material from the same species has been discovered, including a dentary bone, a possible maxilla, and further vertebrae from the neck and trunk. A femur, tibia, and additional osteoderms have also been found.<ref name=":0" />

==References== {{Reflist}}

[[Category:Aetosaurs of North America]] [[Category:Late Triassic pseudosuchians]] [[Category:Fossil taxa described in 1985]] [[Category:Prehistoric pseudosuchian genera]]