Diagnoza

Very short prepineal part of the parietal with the high value of the expansion angle of the sutures separating the parietal from the supratemporal, the mean value for the angle is 21.81 (standard deviation 3.51); ontogenetically, the length of the parietal follows the regression formula y = 0.29x – 5.74 (y, length of prepineal part of parietal; x, skull width).

Porównanie

The main character that differentiates the metoposaurid species is the relation of the lacrimal to the orbit (Colbert and Imbrie 1956; Hunt 1989, 1993; Milner 1994; Schoch and Milner 2000; Sulej 2002). The group with the lacrimal external to the orbit includes Buettneria bakeri, Dutuitosaurus ouazzoui, Arganasaurus lyazidi, and Apachesaurus gregorii. The group of species with the lacrimal forming the orbit’s margin includes Buettneria howardensis, B. perfecta, Metoposaurus maleriensis, M. diagnosticus diagnosticus, and M. diagnosticus krasiejowensis.

            The two groups of metoposaurids represent separate lineages (Fig. 73). It seems that in the mid Late Carnian the Buettneria bakeri initiated a new lineage, which had the lacrimal out of the orbit margin. The tendency to decreasing size and depth of the otic notch, and elongation of the interclavicle was already appearent. In the lineage Buettneria howardensis Metoposaurus diagnosticus krasiejowensis, there was a tendency to decrease ossification of various elements. Buettneria has a more ossified braincase than Metoposaurus. The prootic was still preserved in B. perfecta (Wilson 1941) and in B. howardensis (Sawin 1945). In the humerus, scapula, and fibula a similar tendency towards decreased ossification and gracilization is observed. The Buettneria howardensis humerus and scapulocoracoid are more ossified than in its successors. This tendency is well visible in the scapulocoracoid and scapula of B. howardensis, Metoposaurus maleriensis, and M. diagnosticus krasiejowensis (Fig. 74). It seems that in this series the direction of the glenoid of scapula evolved from the lateroventral direction in B. howardensis to posterolateral in Metoposaurus diagnosticus krasiejowensis. This means the more posteriorly directed limbs, which are useful only in water as a paddle. Additionally, the tendency to gracilization of various elements of postcranial skeleton may be connected with an adaptation to the aquatic environment.

Autekologia

Full aquatic predator, prey: fishes

Występowanie geograficzne

Poland

Zasięg czasowy

Late Carnian

Materiały muzealne

Some incomplete articulated skeletons. Hundreds of isolated bones and dozens skulls.

Literatura

Dzik, J. & Sulej, T. 2004. Pierwszy polski dinozaur. 80 pp, Śląskie Wydawnictwo ADAN, Opole.

Dzik, J. & Sulej, T. 2007. A review of the early Late Triassic Krasiejów biota from Silesia, Poland. Palaeontologia Polonica 64, 1-27.

Konietzko-Meier, D., Bodzioch, A., Sander, PM. 2013. Histological characteristics of the vertebral intercentra of Metoposaurus diagnosticus (Temnospondyli) from the Upper Triassic of Krasiejów (Upper Silesia, Poland). Earth and Environmental Science Transactions of the Royal Society of Edinburgh 103: 237–250.

Konietzko-Meier, D., & Klein, N. 2013. Unique growth pattern of Metoposaurus diagnosticus krasiejowensis (Amphibia, Temnospondyli) from the upper Triassic of Krasiejów, Poland. Palaeogeography, Palaeoclimatology, Palaeoecology 370: 145–157.

Konietzko-Meier, D., & Sander, PM. 2013. Long bone histology of Metoposaurus diagnosticus (Temnospondyli) from the Late Triassic of Krasiejów (Poland) and its paleobiological implications. Journal of Vertebrate Paleontology 33: 1003–1018.

Konietzko-Meier, D., & Schmidt, A. 2013. A histological study of a femur of Plagiosuchus, a Middle Triassic temnospondyl amphibian from southern Germany, using thin sections and micro-CT scanning. Netherlands Journal of Geosciences 92: 65–71

Konietzko-Meier, D., Danto, M, Gądek, K. 2014. The microstructural variability of the intercentra among temnospondyl amphibians. Biological Journal of the Linnean Society 112 , 747–764

Sulej, T. 2002. Species discrimination of the Late Triassic labyrinthodont Metoposaurus diagnosticus. Acta Palaeontologica Polonica 47, 535–546.

Sulej, T. 2007. Osteology, variability, and evolution of Metoposaurus, a temnospondyl from the Late Triassic of Poland. Palaeontologia Polonica 64, 29–139.