Petrolacosaurus ("rock lake lizard") is an extinct genus of diapsid reptile from the late Carboniferous period. It was a small, 40-centimetre (16 in) long reptile, and one of the earliest known reptile with two temporal fenestrae (holes at the rear part of the skull). This means that it was at the base of Diapsida, the largest and most successful radiation of reptiles that would eventually include all modern reptile groups, as well as dinosaurs (which survive to the modern day as birds) and other famous extinct reptiles such as plesiosaurs, ichthyosaurs, and pterosaurs. However, Petrolacosaurus itself was part of Araeoscelida, a short-lived early branch of the diapsid family tree which went extinct in the mid-Permian.
pectoral girdle in Petrolacosaurus is light in comparison to the massive girdles found in taxa such as pelycosaurs. Petrolacosaurus specimens had a clavicle...
Carboniferous to the Early Permian. The group contains the genera Araeoscelis, Petrolacosaurus, the possibly aquatic Spinoaequalis, and less well-known genera such...
specifically, the most inclusive clade containing Captorhinus aguti and Petrolacosaurus kansensis but not Procolophon trigoniceps, by Tsuji and Müller (2009)...
appear as a giant tarantula-like spider hunting the cat-sized reptile Petrolacosaurus in the segment detailing the Carboniferous, with the reconstruction...
Fossils of the basal pelycosaur Archaeothyris and the basal diapsid Petrolacosaurus are also found in the same region of Nova Scotia, although from a higher...
the Joggins Formation in Nova Scotia, and possibly New Brunswick. Petrolacosaurus, the earliest known diapsid reptile, lived during the late Carboniferous...
such as Petrolacosaurus, in that its teeth were larger and blunter; possibly they were used for cracking insect carapaces. Unlike Petrolacosaurus, which...
302–0 Ma PreꞒ Ꞓ O S D C P T J K Pg N Skull diagram of the araeoscelidian Petrolacosaurus kansensis Nile crocodile (Crocodylus niloticus) Scientific classification...
Araeoscelis (9) but more than Petrolacosaurus (6). The maxilla has about 25 teeth, more than Araeoscelis (19) but less than Petrolacosaurus (35). The fourth and...
"Younginiformes" (later, more specifically, emended to Youngina capensis) than to Petrolacosaurus. The cladogram presented here illustrates the "family tree" of reptiles...
seed plants over ferns and lycophytes. First diapsid reptiles (e.g. Petrolacosaurus). 280 Ma Earliest beetles, seed plants and conifers diversify while...
cliffs, the same locality in which the early reptiles Hylonomus and Petrolacosaurus (both of which resemble Archaeothyris) were found. Archaeothyris lived...
most modern reptiles and mammals. Westlothiana Casineria Hylonomus Petrolacosaurus Archaeothyris Carboniferous tetrapods Arjan, Mann, et al. “Carbonodraco...
found by separating it from a block that also contained the remains of Petrolacosaurus and Haptodus. The evolutionary significance of the taxon wasn't realized...
in Kansas, United States, was one of the first diapsids, along with Petrolacosaurus. It was also the first reptile to return to the water, evolving shortly...
Mesothelae suborder. The coal forest is also inhabited by the early reptile Petrolacosaurus, one of the few creatures that end up surviving a catastrophic forest...
proportions—especially the large manus—are similar to the araeoscelidan Petrolacosaurus. In 2024, Rossi and colleagues published the results of several detailed...
(such as Youngina). However, they were not found to be as basal as Petrolacosaurus, one of the earliest and most primitive diapsids known. Although drepanosaurs...
one of two holes in the side of the head. In early diapsids such as Petrolacosaurus and Youngina, the quadratojugal is long as in amphibians, early synapsids...
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