Name Meaning: Catches with Nose
Geologic Era: Permian
Location Discovered: Texas
Size: 40-80 cm long
Estimated Range: North America, Europe, Asia, Africa
Extinction Date: Very early Triassic
Captorhinus and its kin were some of the first true reptiles. Early members of this group of reptiles had one row of teeth, while later forms had multiple rows. Our specimen, a jaw fragment, still has rocky matrix around it. The fossilized bone is a dark grey color, which can be seen sticking out from the rock. Several teeth are plainly visible.
Holes in a skull allow for more muscle attachment. No fenestrae, as Captorhinus and its relatives had, meant minimal area for minimal attachment for jaw muscles, meaning a very weak bite. This meant animal that was not likely to be able to bite through tough prey, such as mollusks or large arthropods. This would have restricted Captorhinus to smaller prey such as small insects and possibly smaller reptiles and amphibians.
Captorhinus would also have had a sprawling gait similar to modern reptiles. It’s movement would have been similar to the modern iguana, so this probably was not an especially fast animal. Most reptiles, including the most basal ones like Captorhinus, had femurs that were oriented almost parallel to the ground. This arrangement does not allow for bipedal motion except in very brief instances.
Captorhinus was one of the victims of the Permian-Triassic extinction, though a few types persisted longer. It was ultimately out-competed by the newly evolved dinosaurs. Dinosaurs could carry their legs directly underneath their trunks. This allowed for swifter, more efficient movement. Captorhinus leaves behind no direct descendants, though turtles were once though to be descended from Captorhinid animals. This ultimately proved to not be the case, which leaves Captorhinus as an initially successful animal, but eventually an evolutionary dead end.
Full Reconstruction: By Nobu Tamura (http://spinops.blogspot.com) (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
Skeleton: Photo taken by Hilary Sifling of Field Museum of Natural History specimen