Diagnoza

Small frog (less than 50 mm snout-vent length) with an anteriorly extended iliac shaft but retaining relatively long neural arches, unfused epipodials, a series of unfused caudal vertebrae instead of an urostyle, a scapulocoracoid that is a single ossification, and an ilium with very strong dorsal prominence and a slender elongate shaft, rounded in cross-section. 

Porównanie

Czatkobatrachus shows a combination of primitive and derived character states that place it near the ancestry of anurans. It differs from Triadobatrachus in having a long slender scapular blade (short and broad in Triadobatrachus), in having a single atlas ossification with no trace of rib facets, a higher level of ossification, long fused posterior transverse processes and sacral ribs, and fully ossified components in elbow joint. Ischium fused to ilium is the feature unique within the Anura. Many of Czatkobatrachus characters (humeral morphology, ilio-sacral morphology, scapula shape, the fusion of the transverse processes) position  it above Triadobatrachus, but these differences could relate to function and lifestyle, if Triadobatrachus were less terrestrial. The most obvious derived characters shared by Czatkobatrachus, Triadobatrachus and the Anura relate to the pelvis (i.e., the anteriorly elongate ilium and, consequently, posterior position of the acetabulum with respect to the ilio-sacral joint, and the reduced pubis). The ilium is less elongate than it is in frogs but more so than in Triadobatrachus.

Autekologia

The fusion of the ribs to the vertebrae, strong transverse processes and  the tail probably reduced in lengt suggest a shift in locomotor pattern away from lateral undulation toward greater dependence on the limbs. The development of a slender scapula, and a large circular glenoid facing laterad within a basically arciferal pectoral girdle might be Czatkobatrachus autapomorphies related to the importance of the forelimbs in propping up the body, in a stage transitional between caudate-like locomotion and that of anurans.

The orientation of the iliac blade implies that thrust forces from the legs were already being directed anteriorly parallel to the body axis, even if the animal was not yet leaping. The ilium was still positioned lateral to the sacral transverse process at the ilio-sacral joint, but was stabilised both dorsally and ventrally by parts of the sacral diapophysis.

The retention of fore- and hind limbs of similar length is a primitive character, compared to the disparity in typical anurans. Czatkobatrachus was a small agile terrestrial animal that walked, and perhaps hopped, with a stiffened back, and a reduced tail. It was substantially smaller than Triadobatrachus, was longer limbed, and would have been more agile. It was probably also more fully terrestrial, judging by the higher degree of ossification throughout the skeleton (even by comparison with basal crown-group taxa).

The reconstructed palaeoenvironment for Czatkobatrachus was a small non-permanent water body (or group of such water bodies), surrounded locally by vegetation (oasis), but in a rather arid environment.

Czatkobatrachus is not uncommon in its assemblage suggests that the anurans originated in upland habitats.

Występowanie geograficzne

Only locus typicus

Zasięg czasowy

Only stratum typicum

Materiały muzealne

Institute of Paleobiology PAN, Warsaw (ZPAL)

Literatura

Borsuk-Białynicka, M. & Evans, S.E. 2002. The scapulocoracoid of an Early Triassic stem-frog from Poland. Acta Palaeontologica Polonica 47, 79–96.

Evans S.E. & Borsuk-Białynicka, M. 1998. A stem-group frog from the Early Triassic of Poland. Acta Palaeontologica Polonica 43, 573–580.

Evans, S.E. & Borsuk-Białynicka, M. 2009. The Early Triassic stem-frog Czatkobatrachus from Poland. Palaeontologica Polonica 65, 79–105.

Shishkin, M.A. & Sulej, T. 2009. The Early Triassic temnospondyls of the Czatkowice 1 tetrapod assemblage. Palaeontologia Polonica 65, 31–77.