Amphibian Body Impressions from the Mississippian of Pennsylvania, USA

Abstract

Temnocorpichnus isaacleai is a new ichnogenus and ichnospecies of temnospondyl amphibian body impression from the Mississippian (Visean) Mauch Chunk Formation of eastern Pennsylvania, UnitedStates. The shovel-shaped head, robust limbs, relatively short trunk and smooth integument diagnose the ichnotaxon and readily distinguish it from Hermundurichnus and Sauropleura, the only other named body impressions of Paleozoic tetrapods. Temnocorpichnus is a compound ichnogenus in which the footprint ichnogenus Batrachichnus is a behaviorally distinct component. The temnospondyl identity of Temnocorpichnus adds to the sparse and earliest records of temnspondyls, which are of Visean age. The smooth integument of the ichnogenus does not support the presence of ventral scales or armor in the earliest temnospondyls, but body proportions of the Mauch Chunk body impressions indicate a relatively terrestrial temnospondyl not matched by any taxon now known from bones. Three closely associated impressions ofTemnocorpichnus on a single bedding plane suggest some sort of gregarious behavior in Mississippian temnospondyls and may support speculation that internal fertilization and associated courtship behavior evolved independently in one group of amphibians more than 300 million years ago.

Variability of growth pattern observed in Metoposaurus krasiejowensis humeri and its biological meaning

“…However, this hypothesis is difficult to prove and highly speculative as there is not much known about sexual features and mating behavior among Temnospondyli. An exceptional case of preservation of three body impressions of Mississippian temnospondyl from the Mississippian (Visean) of eastern Pennsylvania, USA suggest some sort of gregarious behavior and may indicate that internal fertilization occurred in temnospondyls (Lucas et al 2010). In another study carried out on branchiosaurids, an observation on different fossilization of the chorda dorsalis has been made (Werneburg 2008) resulting as a very distinctive dimorphism.…”

Unique trackway on Permian Karoo shoreline provides evidence of temnospondyl locomotory behaviour

“…Although the presence of multiple body impressions on a single bedding plane in other localities has been interpreted as representing some type of gregarious, possible even mating behaviour–as suggested for Temnocorpichnus isaacleai [ 100 ], we consider the impressions to represent the behaviour of one, maybe two individuals. This interpretation is based on the fact that many of the impressions appear to follow on from one another and are sometimes linked by the smoothed swim traces to form two circular routes.…”

“…Body impressions of amphibians showing most or all of the body outline are rare, with only three named ichnospecies described from the Palaeozoic, Hermundurichnus fornicatus [96,97] and Sauropleura longicaudata [98,99] from the Carboniferous-Permian of Europe and Temnocorpichnus isaacleai from the late Mississippian of eastern Pennsylvania in North America [100][101][102][103]. Amphibian body resting traces associated with trackways and swimming traces have previously been described by Turek (1989), but were not named.…”