Captorhinidae is an extinct family of tetrapods, traditionally considered primitive Reptile, known from the late Carboniferous to the Late Permian. They had a cosmopolitan distribution across Pangea.
Description
Captorhinids are a clade of small to very large lizard-like animals that date from the Late Carboniferous through the
Permian. Their
were much stronger than those of their relatives, the
, and had teeth that were better able to deal with tough plant material. The
skeleton is similar to those of
and
; these animals were grouped together with the captorhinids in the order
Cotylosauria as the first
reptiles in the early 20th century,
but are now usually regarded as
Stem group-
no closer to reptiles than to
. Captorhinids have broad, robust skulls that are generally triangular in shape when seen in dorsal view. The
are characteristically downturned. The largest captorhinid, the herbivorous
Moradisaurus, could reach an estimated snout-vent length of 2 meters (6.5 feet).
[ Multiple tooth-rowed captorhinids from the early Permian fissure fills of the Bally Mountain Locality of Oklahoma] Early, smaller forms possessed single rows of teeth, and were likely carnivorous or omnivorous, while the larger, more derived captorhinids belonging to the subfamily Moradisaurinae were herbivorous and developed multiple (up to 11) rows of teeth in the jaws alongside propalinal (back and forth) jaw motion, which created an effective apparatus for grinding and shredding plant matter.
Histological and SEM analysis of captorhinid tail vertebrae concluded in a 2018 study that captorhinids were the first amniotes to develop Autotomy as a defensive function. In studied specimens a split line is present in certain caudal vertebrae that is similar to those found in modern reptiles that perform caudal autonomy. This behaviour represented significant evolutionary benefit for the animals, allowing for escape and distracting predators, as well as minimizing blood loss at an injury site.
Classification
Taxonomy
The following taxonomy follows Reisz
et al., 2011 and Sumida
et al., 2010 unless otherwise noted.
Euconcordia cunninghami is thought to be the basalmost known member of Captorhinidae. A phylogenic study of primitive reptile relationships by Muller & Reisz in 2006 recovered
Thuringothyris as a sister taxon of the Captorhinidae.
[Muller, J. and Reisz, R.R. (2006). "The phylogeny of early eureptiles: Comparing parsimony and Bayesian approaches in the investigation of a basal fossil clade." Systematic Biology, 55(3):503-511. ] The same results were obtained in later phylogenic analyses.
Captorhinidae contains a single subfamily, the Moradisaurinae. Moradisaurinae was named and assigned to the family Captorhinidae by A. D. Ricqlès and P. Taquet in 1982. Moradisaurinae was defined as "all captorhinids more closely related to Moradisaurus than to Captorhinus". The moradisaurines inhabited what is now China, Morocco, Niger, Russia, Texas and Oklahoma.
Captorhinids were once thought to be the ancestors of . The Guadalupian reptile Eunotosaurus from South Africa was seen as the "missing link" between cotylosaurs and chelonians throughout much of the early 20th century.
Phylogeny
The cladogram below follows the topology from a 2011 analysis by paleontologists Robert R. Reisz, Jun Liu, Jin-Ling Li and Johannes Müller.
[
]
Traditional classification of Captorhinidae within Eureptilia, after Muller and Reisz (2006):
