There may be other new species waiting to be found at the Arlington Archosaur
Site because it contains the remains of an ecosystem that flourished between 95 million and 100 million years ago.
The new lungfish tooth plates discussed herein were recovered from Lewisville Member exposures occurring at a productive new Texas fossil locality; the Arlington Archosaur
Representing a broad range of depositional environments, ranging from perennial lacustrine to fluvial and aeolian settings, and documented by hundreds of fossils, these assemblages lack any of the characteristic Late Triassic faunal elements, most conspicuously metoposaurid temnospondyls, phytosaurs, procolophonids, and diverse non-crocodylomorph and non-dinosaurian archosaurs
, all of which are known from older assemblages in the Fundy basin and elsewhere.
It further implies that one-way airflow evolved in archosaurs
earlier than once thought, and may explain why those animals came to dominance in the Early Triassic Period, after the extinction and when the recovering ecosystem was warm and dry, with oxygen levels perhaps as low as 12 percent of the air compared with 21 percent today.
Dinosaurs belong to a larger group called archosaurs
that about 250 million years ago cleaved into two branches: crocodilians in one and another that includes dinosaurs, extinct flying reptiles called pterosaurs, and birds, which evolved from feathered dinosaurs.
The researchers were able to infer the genome sequence of the common ancestor of birds and crocodilians (archosaurs
) and therefore all dinosaurs, including those that went extinct 66,000,000 years ago.
Archosaurian reptiles from the Evangeline Member comprise various taxa of crocodile-line archosaurs
Today the tree is divided into three main branches (note that the pterosaurs and crurotarsans are archosaurs
but not dinosaurs).
The breathing method is believed to have first appeared in ancient reptiles called archosaurs
which dominated the Earth 251 million years ago.
Dinosaurs and crocodiles belong to a group of large reptiles known as archosaurs
, which prowled the earth during the Mesozoic Era, some 256 million years ago, when man's nearest ancestors were primitive mammals no bigger or complex than the common shrew.
We also discuss flying & swimming archosaurs
and other animals of that period as well as earlier and later periods.