Biotic and abiotic factors and the phylogenetic structure of extinction in the evolution of Tethysuchia

Crocodylomorpha is a large and diverse clade with a long evolutionary
history now restricted to modern crocodylians. Tethysuchia is a
less-inclusive clade of semi-amphibious taxa that crossed two biological
crises: the second Oceanic Anoxic Event (OAE 2) and the
Cretaceous/Paleogene (K/Pg) Crisis. Numerous studies have sought to find
the driving factors explaining crocodylomorph evolution producing
contradictory conclusions. Studies of included groups may be useful. Here,
we study factors driving tethysuchian evolution using phylogenetically
informed statistical analyses. First, we tested the phylogenetic structure
of tethysuchian extinction at the OAE 2 and K/Pg crises. We then used
phylogenetic comparative methods to test the influence of intrinsic (body
size, snout proportion) and extrinsic (temperature, paleolatitude) factors
on the evolution of tethysuchian diversity at the OAE 2 and the K/Pg
crises. Finally, we tested whether temperature influenced the evolution of
body size. We conclude that (1) extinction was not random in regards to
phylogeny for Tethysuchia at the OAE 2 and K/Pg crises; (2) while an
important tethysuchian turnover follows OAE 2, the K/Pg crisis was
followed by an explosion in diversity of tethysuchians, probably linked to
the colonization of emptied ecological niches; (3) tethysuchians lived in
warmer environments after the OAE 2 crisis, possibly because of both
global warming and latitude distribution shifts; (4) there is a
significant change of snout proportion after the OAE 2 and the K/Pg
crises, likely caused by niche partitioning; and (5) there is a positive
correlation between body size and temperature, possibly because of a
longer growth season