Phytosaurs were long considered early crocodile-line archosaurs
but Nesbitt (2011) recently placed them outside crown-group Archosauria.
It included 74 taxa coded for 240 characters, with the non-crocodylomorph pseudosuchian archosaur
Postosuchus kirkpatricki used as the outgroup taxon.
That means one-way airflow may have arisen not among the early archosaurs
about 250 million years ago, but as early as 270 million years ago among cold-blooded diapsids, which were the common, cold-blooded ancestors of the archosaurs
and Lepidosauromorpha, a group of reptiles that today includes lizards, snakes and lizard-like creatures known as tuataras.
and the early to late Cretaceous transition in North-Central Texas.
evolved along two different paths, one of which gave rise to the crocodilian ancestors of crocodiles and alligators.
He then outlines the history of nineteenth and early 20th-century ideas concerning the origin of birds in a chapter (Descent of Birds) that begins with an introduction to basal archosaurs
and is followed by a somewhat puzzling brief on cladistic methodology, an indictment of the method, and a critique of the currently fashionable "theropod-bird" hypothesis.
We also discuss flying & swimming archosaurs
and other animals of that period as well as earlier and later periods.
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.
The snapshot of life 10 million years after the extinction reveals that, among other things, archosaurs
roamed in Tanzanian and Zambian basins, but weren't distributed across southern Pangea as had been the pattern for four-legged animals before the extinction.
eggshell consists of laterally juxtaposed calcium carbonate crystals (aragonitic for chelonians or calcitic for archosaurs
) (Erben, 1970; Packard and DeMarco, 1995) on an organic network (Kohring and Reitner, 1996; Packard and DeMarco, 1995), regularly grouped in eggshell units that nuleate from an underlying membrana testacea (MT) in Dinosauria (Pooley, 1979, Mikhailov, 1992).
Efficient one-way breathing may have given archosaurs
a boost: Work shows oxygen levels in their time were about half of today's, lower than available at the top of Mount Everest.
, and the Early to Late Cretaceous transition in north-central Texas.
were among the dominant land animals during the Triassic period 250 million to 200 million years ago and include dinosaurs, crocodiles and their kin.
It was recognized a diversity of vertebrate fauna composed by semionotiform fishes, at least one lepidosaur taxon, and representatives of three groups of archosaurs
, such as crocodylomorphs, pterosaurians and dinosaurs.
What's interesting is that when you do that, you see the origins of the features that make the bird head special lie deep in the history of the evolution of Archosaurs
, a group of animals that were the dominant, meat-eating animals for millions of years.