Sierritasuchus
Encyclopedia
Sierritasuchus is an extinct genus
of aetosaur
in the subfamily Desmatosuchinae
. It is known from a small holotype
skeleton from the Late Triassic
Tecovas Formation
of Texas
. This skeleton (known as UMMP V60817) was discovered in 1939 and was originally assigned to the genus Desmatosuchus
. It was placed in its own genus in 2008 after having been in the collections of the University of Michigan Museum of Paleontology, with the type species
being S. macalpini. The generic name refers to Sierrita de la Cruz Creek where the holotype was found, and the specific name refers to Archie MacAlpin, who discovered the skeleton. Based on the histology
of the scute
s of the holotype, the individual was a subadult that was not fully grown.
Sierritasuchus can be distinguished from other aetosaurs by several unique features as well as a distinct combination of features in its scutes. Unlike other aetosaurs, Sierritasuchus has recurved spines along its side that are serrated on the front edges. Additionally, there is a distinct ridge on the posterior surface of each dorsal eminence. Dorsal eminences are small projections on the surfaces of paramedian scutes that line the back of the animal on either side of the vertebral column
. In Sierritasuchus, the dorsal eminence touches the posterior margin of the paramedian scute. Each paramedian scute is covered in a random pattern of pits. Both the paramedian and lateral scutes (which run along the side of the animal beneath the paramedians) have anterior bars.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of aetosaur
Aetosaur
Aetosaurs are an extinct order of heavily armoured, medium- to large-sized Late Triassic herbivorous archosaurs. They have small heads, upturned snouts, erect limbs, and a body covered by plate-like scutes. All aetosaurs belong to the family Stagonolepididae...
in the subfamily Desmatosuchinae
Desmatosuchinae
Desmatosuchinae is one of the two subfamilies of aetosaurs, the other being Aetosaurinae. It is a stem-based taxon defined as all aetosaurs more closely related to Desmatosuchus than the last common ancestor of Desmatosuchus and Stagonolepis. All synapomorphies that diagnose the clade can be found...
. It is known from a small holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
skeleton from the Late Triassic
Late Triassic
The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...
Tecovas Formation
Tecovas Formation
-Vertebrate fauna:...
of Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
. This skeleton (known as UMMP V60817) was discovered in 1939 and was originally assigned to the genus Desmatosuchus
Desmatosuchus
Desmatosuchus is an extinct genus of archosaur belonging to the Order Aetosauria. It was one of the largest aetosaurs, being long and about 1.50 m high. It lived during the Late Triassic in Texas....
. It was placed in its own genus in 2008 after having been in the collections of the University of Michigan Museum of Paleontology, with the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
being S. macalpini. The generic name refers to Sierrita de la Cruz Creek where the holotype was found, and the specific name refers to Archie MacAlpin, who discovered the skeleton. Based on the histology
Histology
Histology is the study of the microscopic anatomy of cells and tissues of plants and animals. It is performed by examining cells and tissues commonly by sectioning and staining; followed by examination under a light microscope or electron microscope...
of the scute
Scute
A scute or scutum is a bony external plate or scale, as on the shell of a turtle, the skin of crocodilians, the feet of some birds or the anterior portion of the mesonotum in insects.-Properties:...
s of the holotype, the individual was a subadult that was not fully grown.
Sierritasuchus can be distinguished from other aetosaurs by several unique features as well as a distinct combination of features in its scutes. Unlike other aetosaurs, Sierritasuchus has recurved spines along its side that are serrated on the front edges. Additionally, there is a distinct ridge on the posterior surface of each dorsal eminence. Dorsal eminences are small projections on the surfaces of paramedian scutes that line the back of the animal on either side of the vertebral column
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
. In Sierritasuchus, the dorsal eminence touches the posterior margin of the paramedian scute. Each paramedian scute is covered in a random pattern of pits. Both the paramedian and lateral scutes (which run along the side of the animal beneath the paramedians) have anterior bars.
External links
- Sierritasuchus in the Paleobiology DatabasePaleobiology Database' is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms.-History:The Paleobiology Database was founded in 2000. It has been funded by the National Science Foundation and the Australian Research Council...