The Kids Were Scarier: Cranial Ornamentation DECREASE With age in Early Triassic Trematosauroid Temnospondyl Benthosuchus?

On the development of surface ornamentation of skull bones in the ontogeny of Early Triassic benthosuchids (Amphibia, Temnospondyli)

Author:

Morkovin

Abstract:

The rate of developmental changes in ornamentation of the dermal skull observed at the submature stages of the trematosauroid Benthosuchus (Amphibia, Temnospondyli) shows a wide range of individual variation divided into two dominant modes. The analysis of this variation based on comparisons within samples of two dermal bones (supratemporal and squamosal) displays that such a bimodality is distinctly expressed at the earliest known growth stage and tends to disappear with age.

Drivers of Marine Tetrapod Evolution From the Triassic Mesozoic to the Quaternary Cenozoic

Marine tetrapod macroevolution: Physical and biological drivers on 250 million years of invasions and evolution in ocean ecosystems

Authors:

Pyenson et al

Abstract:

The dominant consumers in today’s ocean ecosystems are marine mammals, including cetaceans, sirenians, and pinnipeds, and other marine carnivorans. The ecological dominance of marine mammals can be traced back to at least seven independent transitions during the Cenozoic, when different lineages of terrestrial mammals underwent land to sea evolutionary transformations. However, the evolution of marine mammals represents only the most recent set of marine invasions by tetrapods over the past 250 million years. During the Mesozoic, over a dozen different reptile lineages (e.g., mosasaurs, ichthyosaurs, turtles, snakes) evolved obligate marine lineages, including a few lineages that persist to today, such as sea turtles. Birds, which are phylogenetically nested among diapsid reptiles, have also repeatedly adapted to marine life since the Cretaceous. Attempts to understand the common patterns of marine tetrapod evolution, and the processes that have shaped them, have largely been limited to individual groups. Placed in a broad comparative view from the Mesozoic to the Cenozoic eras, the macroevolution of marine tetrapods reveals evolutionary drivers at different scales, along with morphological parallels, unique evolutionary innovations, and the strong influence of historical constraints. Major physical, environmental drivers appear to be responsible for some patterns in marine tetrapod evolution at some temporal and geographic scales, but these drivers are not unique causes, as biological drivers (e.g., escalation) likely also play a role. The culmination of this trophic ascendancy has been dramatically altered by human hunting (especially of marine mammals), underscoring the need for historical datasets that extend into deep time to understand the ecological history of marine tetrapods.

Calamops is Really a Trematosaur

Anatomy and phylogenetic relationships of Calamops paludosus (Temnospondyli, Stereospondyli) from the Triassic of the Newark Basin, Pennsylvania

Authors:

1. Hans-Dieter Sues (a)
2. Rainer R. Schoch (b)

Affiliations:

a. Department of Paleobiology, National Museum of Natural History , MRC 121, Smithsonian Institution , P.O. Box 37012, Washington , D.C. , 20013-7012 , U.S.A.

b. Staatliches Museum für Naturkunde Stuttgart , Rosenstein 1, D-70191 , Stuttgart , Germany

Abstract:

The holotype of the large temnospondyl Calamops paludosus is the oldest known tetrapod fossil from the Triassic of the Newark basin in Pennsylvania. Although it is usually placed in Metoposauridae, its affinities have remained unknown since its original description because the unique specimen had never been prepared. Preparation and casting of the specimen, which comprises three pieces of a left mandibular ramus, now permits detailed anatomical description of the jaw and assessment of its affinities. Calamops paludosus is a valid taxon of trematosauroid temnospondyls that can be diagnosed by several autapomorphies. It represents one of the geologically youngest known records of long-snouted trematosaurs and the first record of these temnospondyls from the Late Triassic of North America.