Biology:Prozostrodontia

From HandWiki
Short description: Clade of cynodonts

Prozostrodonts
Temporal range: Late Triassic (Carnian),
233.23–0 Ma

Kayentatherium wellesi.jpg
Skull of Kayentatherium wellesi
Indian Bison Gobo.jpg
Gaur
Scientific classification e
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Clade: Therapsida
Clade: Cynodontia
Clade: Probainognathia
Clade: Prozostrodontia
Liu and Olsen, 2010
Subgroups

Prozostrodontia is a clade of cynodonts including mammaliaforms and their closest relatives such as Tritheledontidae and Tritylodontidae. It was erected as a node-based taxon by Liu and Olsen (2010) and defined as the least inclusive clade containing Prozostrodon brasiliensis, Tritylodon langaevus, Pachygenelus monus, and Mus musculus (the house mouse). Prozostrodontia is diagnosed by several characters, including:

  • Reduced prefrontal and postorbital bones, with the disappearance of a strut of bone called the postorbital bar separating the eye socket from the temporal region
  • Unfused symphysis between the dentary bones in the lower jaw
  • The presence of a small hole within the eye socket called the sphenopalatine foramen
  • A long sagittal crest extending to the rearmost part of the lambdoidal crest at the back of the skull
  • Neural spines of the dorsal vertebrae angled backward
  • A convex-shaped iliac crest and a reduced posterior iliac spine on the hip
  • An acetabular notch on the ischium (a groove in the hip socket)
  • The position of a small projection called the lesser trochanter close to the head of the femur[3]

Prozostrodontia includes tritylodontids, which have traditionally been placed within the more primitive cynodont group Cynognathia as distant mammal relatives. It also includes Tritheledontidae, which has long been placed close to mammals. Most previous studies considered Tritheledontidae a valid monophyletic grouping, meaning it was a true clade including all the descendants of a single common ancestor, but Liu and Olsen (2010) found Tritheledontidae to be a paraphyletic series of basal prozostrodontians. Below is a cladogram from Liu and Olsen (2010) showing the phylogenetic position of Prozostrodontia:[3]

Cynodontia 

Procynosuchus

Galesaurus

Thrinaxodon

Platycraniellus

Eucynodontia
Cynognathia

Cynognathus

Gomphodontia

Diademodon

Langbergia

Trirachodon

Sinognathus

Traversodontidae

Pascualgnathus

Luangwa

Scalenodon angustifrons

Scalenodon hirschoni

Massetognathus

Exaeretodon

Probainognathia

Ecteninion

Chiniquodon

Probainognathus

Prozostrodontia

Prozostrodon

Therioherpeton

Riograndia

Pachygenelus

Tritylodontidae

Oligokyphus

Kayentatherium

Tritylodon

Bienotherium

Brasilodon

Mammalia

Adelobasileus

Sinoconodon

Morganucodon

References

  1. Martinelli, A. G.; Eltink, E.; Da-Rosa, Á. A. S.; Langer, M. C. (2017). "A new cynodont from the Santa Maria formation, south Brazil, improves Late Triassic probainognathian diversity". Papers in Palaeontology 3 (3): 401–423. doi:10.1002/spp2.1081. 
  2. Stefanello, M.; Martinelli, A. G.; Müller, R. T.; Dias-da-Silva, S.; Kerber, L. (2023). "A complete skull of a stem mammal from the Late Triassic of Brazil illuminates the early evolution of prozostrodontian cynodonts". Journal of Mammalian Evolution. doi:10.1007/s10914-022-09648-y. 
  3. 3.0 3.1 Liu, J.; Olsen, P. (2010). "The Phylogenetic Relationships of Eucynodontia (Amniota: Synapsida)". Journal of Mammalian Evolution 17 (3): 151. doi:10.1007/s10914-010-9136-8. 

Wikidata ☰ Q5852697 entry