Two new Species of Lepospondyl Batropetes From Permian Germany

Two new species of the genus Batropetes (Tetrapoda, Lepospondyli) from the Central European Rotliegend (basal Permian) in Germany

Author:

Glienke

Abstract:

Two new species of Batropetes are described from the Lower Rotliegend of the Saar-Nahe Basin in western Germany. Batropetes palatinus, sp. nov., is characterized by a narrow, anteriorly elongated prefrontal, a slender postfrontal without an anterolateral process, a trapezoid postorbital, and a large quadrate in exterior view. Batropetes appelensis, sp. nov., is characterized by a high angular, ‘Z’-shaped angular-dentary suture, no indentation between stem and plate of interclavicle, and scapulocoracoid without ossified coracoid. The genus Batropetes is characterized by an average length of almost 8 cm, a short trunk with 17 or 19 presacrals depending on the species, large orbit with a raised rim, a large pineal foramen, three pits on the frontal, tricuspid teeth, a toothless palate, four short robust limbs, and completely ossified pectoral and pelvic girdles (except for the coracoids of B. appelensis and B. fritschi). Batropetes belongs to the Brachystelechidae, together with Carrolla and Quasicaecilia. Cladistic analysis reveals for the monophyletic genus Batropetes that B. appelensis forms a sister group to the remaining three species in the genus, and B. niederkirchensis is the sister group to B. palatinus and B. fritschi. The functional interpretation of the appendicular skeleton and the skull morphology suggest that all Batropetes species were terrestrial, living near the lakes in which they were preserved. They appear to have fed on small arthropods in the leaf litter or in the upper zone of the soil.

Some Remarkable Walking-to-Swimming Transition Trackways From Early Permian Europe

Transition between terrestrial-submerged walking and swimming revealed by Early Permian amphibian trackways and a new proposal for the nomenclature of compound trace fossils

Authors:

Petti et al

Abstract:

Exceptionally preserved Early Permian tetrapod trackways from the Orobic Basin (Central-Western Southern Alps) offer a unique opportunity to investigate in detail locomotion in fossil vertebrates that lived on continental European landmasses. Herein are reported the results of a study on several tetrapod trackways that display a large variety of behavioural, gait and substrate related extramorphologies. They clearly document the transition from terrestrial-underwater walking to swimming and are assigned to the compound ichnotaxon Batrachichnus C Lunichnium. The use of the “C” symbol is here introduced for the first time as nomenclatural indication of a Compound trace. Producers were probably small-sized temnospondyl or lepospondyl (microsaurs) amphibians. Comparisons with living urodelan anatomy and mechanics provide evidence for conservatism of locomotor mechanics in evolutionary history among amphibians. The derived model for locomotor kinematics in Early Permian amphibians provides a reference for interpreting transitional land-to-water trackways. The shift from walking to swimming behaviour in early tetrapods, as in extant urodelan amphibians, is described as a complex balance between different dynamics.

Carboniferous Lepospondyls did not Undergo Metamorphosis

Morphometric analysis of skeletal growth in the lepospondyls Microbrachis pelikani and Hyloplesion longicostatum (Tetrapoda, Lepospondyli)

Authors:

Jennifer C. Olori

Abstract:

Although morphological evidence alone appears insufficient to resolve the problem of extant amphibian ancestry, comparison of developmental processes and functional correlates of ontogenetic change may provide a basis for evaluating relationships among extinct and extant tetrapods. In the first allometric study of cranial and postcranial growth in any lepospondyl, I investigate skeletal development in the microsaurs Microbrachis pelikani and Hyloplesion longicostatum using traditional measurement-based and geometric morphometric analyses. Regression analyses against both skull and centrum lengths for M. pelikani indicate positive allometric scaling of the interclavicle plate length, pubis, and ilium, and negative scaling of the diameter of the orbit. Preliminary data for H. longicostatum support negative scaling of neural arch height and posterior centrum height. Results from geometric morphometrics suggest slight widening of the cheek in M. pelikani, rather than marked elongation. Overall, cranial and postcranial growth in both microsaurs was primarily isometric and comparison with allometric data from other Paleozoic taxa suggests that isometric growth is an ancestral feature of development in early tetrapods. All regression analyses for M. pelikani and H. longicostatum had a constant linear slope, indicating that ontogenetic trajectories were continuous, with gradual skeletal growth and no shift in feeding or locomotor function during ontogeny. The lack of morphological change suggests that these microsaurs did not undergo an extant amphibian-like metamorphosis that included reorganization of the skeleton. These data support the hypothesis that metamorphosis is a derived mode of development present only in extant amphibians and their closest relatives.

Dimetrodon Demonstrated to be Eating Lepospondyl Diplocaulus in Middle Permian Texas

Talk about a creature feature: A bizarre boomerang-headed amphibian that burrowed in a seasonal pond in what is now Texas often met its doom in the jaws of a reptilian fin-backed mammalian ancestor, new fossils reveal.

These two weird critters were residents of the Permian period 298 million to 250 million years ago, before dinosaurs roamed the Earth. Dimetrodon, the jaguar-size finback, looked like a lizard but was actually more closely related to modern mammals. Diplocaulus, the boomerang-head, was a truly strange amphibian with an impractically wide, bony skull.

[...]

Bakker and his colleagues discovered the Dimetrodon and Diplocaulus interaction in the Craddock bone bed in Baylor County, Texas. The bone bed is scattered with the bodies of boomerang-heads, curled in what were once burrows. The amphibians seem to have burrowed into the mud to survive the dry season, the researchers reported here Monday at the annual meeting of the Geological Society of America.

"The bed had a reputation of just being a stew pot with everything mixed together," Bakker said. "That's totally wrong. It's beautifully layered."

The excavations revealed that boomerang-heads were common in the pond — and that something was snacking on them.

"We have hundreds of these, mostly chewed, and even the guys in burrows got attacked," Bakker said.

The shed teeth, "like bullets in a crime scene," revealed the attacker to be Dimetrodon, he said. The finback's sharp fangs and long snout would have enabled it to bite boomerang-heads hiding in burrows, perhaps after partially excavating them with its sharp, digging claws.

One cluster of eight juvenile boomerang-heads was found stacked together, suggesting they all occupied the same burrow. Dimetrodon likely killed the top three, including one whose nose was bitten clean off (taking part of the brain with it). The other five boomerang-heads survived the Dimetrodon, only to perish during the next dry season, Bakker said.

link.

Are Modern Amphibians Really Lepospondyls?

The origin(s) of extant amphibians: a review with emphasis on the “lepospondyl hypothesis”

Authors:

1. David MARJANOVIĆ (a,b)
2. Michel LAURIN (a)

Affiliations:

a. UMR 7207, CNRS/MNHN/UPMC/Collège de France, Département Histoire de la Terre, case postale 48, 57 rue Cuvier, F-75231 Paris cedex 05, France

b. Abteilung Forschung, Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstraße 43, D-10115 Berlin, Germany

Abstract:

The origins of the extant amphibians (frogs, salamanders, caecilians) remain controversial after over a century of debate. Three groups of hypotheses persist in the current literature: the “temnospondyl hypothesis” (TH) which roots Lissamphibia Haeckel, 1866 (the smallest clade composed of the extant amphibians) within the Paleozoic temnospondyls, the “lepospondyl hypothesis” (LH) which postulates a monophyletic Lissamphibia nested within the Paleozoic lepospondyls, and the “polyphyly hypothesis” (PH), according to which the frogs and the salamanders are temnospondyls while the caecilians are lepospondyls. The discovery of the Middle Jurassic to Pliocene albanerpetontids, which are very similar to the extant amphibians, has complicated rather than resolved this situation. We present a review of recent publications and theses in this field, several of which show more support for the LH than for the TH and considerably more than for the PH. In addition, we show that there is no particular attraction between long-bodied lissamphibians (caecilians) and long-bodied lepospondyls (such as the lysorophians): when they are removed from two published matrices, reanalyses nonetheless find the LH. In one case the LH is found even when all salamanders are removed as well. We furthermore propose that the complex of characters called the salamander mode of autopodium development is (in its less extreme forms) plesiomorphic for limbed vertebrates, so the apparent presence of this mode of development in temnospondyls cannot support the TH or the PH. Still, a consensus will not be reached soon, despite the increasing range of data and types of analysis that are used (morphological, molecular and combined phylogenetics, development biology, molecular divergence dating, paleontological supertree dating, combined dating, and calculation of confidence intervals on first appearances in the fossil record). We present examples of pertinent character state distributions and explore a large gap in the fossil record of small stegocephalians

Warning: the title link is to a PDF.

Is Lissamphibia Paraphyletic?

(cladogram from here)

If Eocaecilia nests within Lepospondyli...that would mean that Caecilians are not closely related to salamanders and frogs at all.

How accepted (or not) is this?