Metoposaurus
Metoposaurus | |
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Skeleton of Metoposaurus diagnosticus krasiejowensi in the Krasiejów museum in Poland | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Order: | †Temnospondyli |
Suborder: | †Stereospondyli |
Family: | †Metoposauridae |
Genus: | †Metoposaurus Lydekker, 1890 |
Species | |
Nomina dubia:
| |
Synonyms | |
Genus-level:
Species-level:
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Metoposaurus meaning "front lizard" is an extinct
Discovery and species
Discovery
The earliest mention of Metoposauridae dates back to 1842 when Von Meyer described the dorsal view of the skull roof of a labyrinthodont from the Keuper Schilfsandstein of Feuerbacher Haide near Stuttgart. Later, Meyer attempted a reconstruction of the same specimen and named it Metopias diagnosticus. However, Lydekker later renamed the species as Metoposaurus diagnosticus in 1890 because the name Metopias was already in use.[5][6]
Species
Based on the position of the
- Metoposaurus diagnosticus (Meyer, 1842)
Fossils were found among other locations in the
- Metoposaurus krasiejowensis (Sulej, 2002)
Fossils were found in the Drawno Beds Formation of Poland. The species has a very short perineal part of the parietal with the high value of the expansion angle of the sutures separating partially from the supratemporal (mean angle value of 21.81). Some skulls possess a large quadrate foramen and small paraquadrate foramen.[5] It had an estimated skull length up to 47.5 cm (18.7 in).[5]
- Metoposaurus algarvensis (Brusatte et al. 2015)
From the Late Triassic
Formerly assigned species
- Metoposaurus maleriensis (Chowdhury, 1965)
Described from the Maleri Formation of Central India,[6] was renamed Panthasaurus maleriensis by Chakravorti and Sengupta (2018).[8]
- Metoposaurus azerouali (Dutuit, 1976)
Described from the Argana Group of Morocco. Reassigned to Arganasaurus by Buffa et al. (2019).[9][10]
Synonyms and nomina dubia
- Metoposaurus stuttgartensis: synonymous, is first described by Fraas (1913) from the Keuper Lehbergstufe of Sonnenberg, near Stuttgart. Fraas identified the species based on the interclavicle and left clavicle, vertebrae and rib fragments which are now located in the Stuttgart Museum.[11]
- Metoposaurus santaecrucis Nomina dubia it was described by Koken (1913) based on the partial skull found in Heiligenkreuz and the specimen is now located in the University Museum of Tübingen.[12]
- Metoposaurus heimi synonymous it was described by Kuhn (1932) based on a complete skull from the middle Keuper Blasensandstein in Upper Franconia. The specimen is currently located in the Museum of Paleontology and Historical Geology, Munich.[5]
Description
Skull
Lacrimal
The
Parietal
A study conducted by Sulej (2007) shows that the parietal contacts the frontal anteriorly, the postfrontal anterolaterally, the supratemporal laterally, and the postparietal posteriorly. The pineal foramen is in the posterior region of the parietal. An interesting feature pointed out by Sulej on examining the skull of Metoposaurus diagnosticus krasiejowensis is that it has a shorter prepineal region of the parietal than Metoposaurus diagnosticus diagnosticus and the expansion angle of the suture separating the parietal from the supratemporal has a lower value.[2]
Maxilla
The maxilla forms a large, completely dentigerous shelf bearing 83 to 107 teeth. The first teeth are large, and tooth size decreases markedly further posteriorly. On the ventral side, the maxilla contacts the ectopterygoid, palatine and vomer. In the choanal region, the maxilla is slightly broadening medially on the palatal side where it borders the choana. The margin of the choana is variable. In most skulls, it is weakly distinguished and rounded, but in a few cases it is more solid and sharply outlined.[5]
Vertebral column
According to Sulej (2007), the intercentra of
Geography and history
Metoposaurids are known from the early Late Triassic (Carnian) Keuper of Germany and Austria. There have also been unconfirmed notifications reported from Madagascar (Dutuit 1978) and China (Yang 1978).[14][15][5] Metoposaurus diagnosticus krasiejoviensis is the most abundant metoposaurid amphibian of the Krasiejów site (the species name comes from the site) located in southern Poland.[16]
Among stereospondyls, metoposaurs seem to have been one of the latest survivors. However, a variety of other temnospondyl lines carried into the Jurassic, the latest of which was another stereospondyl, the chigutisaurid Koolasuchus, discovered in modern-day Australia, where it was supported by a colder mid-Cretaceous climate.
Paleobiology
Locomotion
Examination of the vertebral column and limb articulations of Metoposaurus suggests that they used their limbs as flippers and swam by making simultaneous and symmetrical limb movements similar to plesiosaurs.[5] A recent study conducted in Poland suggests that the broad, flat head and arm bones, wide hands, and large tail of Metoposaurus diagnosticus are significant characteristics which led the researchers to conclude that they swam in ephemeral lakes during the wet season and used their heads and forearms to burrow under the ground when the dry season began. The study found that the medullary region is filled with well-developed trabecular bone. The growth marks in all bones are organized as thick layers of highly vascularized zones and thick compact annuli with numerous rest lines, which may correspond with favorably wet and long, unfavorably dry seasons.[17]
Predators
The exact predators of Metoposaurus are unknown, but
References
- ^ .
- ^ a b c Sulej T (2002). "Species discrimination of the Late Triassic temnospondyl amphibian Metoposaurus diagnosticus". Acta Palaeontologica Polonica. 47: 535–546. https://www.app.pan.pl/archive/published/app47/app47-535.pdf
- PMID 30083441.
- ISBN 978-1-57765-488-9.
- ^ a b c d e f g h i j k Sulej T (2007). "Osteology, variability, and evolution of Metoposaurus, a temnospondyl from the Late Triassic of Poland". Palaeontologica Polonica. 64: 29–139. palaeontologia.pan.pl/PP64/Sulej.pdf
- ^
- ^ Meyer, E. 1842. Labyrinthodonten−Genera. Neues Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefaktenkunde 1842,301–304.
- .
- ^ Dutuit, J.M., 1976. Introduction à l’étude paléontologique du Trias continental marocain. Description des premiers Stegocephales recueillis dans le couloir d’Argana (Atlas occidental). Memoires du Museum National d’Histoire naturelle, Paris. Series C 36: 1–253.
- .
- ^ Fraas, E. 1913. Neue Labyrinthodonten aus der Schwäbischen Trias. Palaeontographica 60, 275–294
- ^ Koken, E. 1913. Beiträge zur Kenntnis der Schichten von Heiligenkreuz (Abteital, Südtirol). Abhandlungen der Kaiserlich−Koniglichen Geologischen Reichsanstalt 16: 1–44.
- ^ Lucas, S.G. and Spielmann, J.A., eds., 2007, The Global Triassic. New Mexico Museum of Natural History and Science Bulletin 41.
- ^ Dutuit, J.M.1978. Description de quelques fragments osseux provenant de la région de Folakara (Trias supérieur Malagache). Bulletin de Museum Nationale d’Histoire naturelle, Paris. Series III 516: 79–89
- ^ Yang, C. 1978. A Late Triassic vertebrate fauna from Fukang, Sinkiang. Memoir of the Institute of Vertebrate Palaeontology and Paleoanthropology 13, 60–67.
- ^ Barycka, Ewa. "Morphology and ontogeny of the humerus of the Triassic temnospondyl amphibian Metoposaurus diagnosticus." Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 243.3 (2007): 351-361.
- ^ Konietzko-Meier, Dorota, and Nicole Klein. "Unique growth pattern of Metoposaurus diagnosticus krasiejowensis (Amphibia, Temnospondyli) from the Upper Triassic of Krasiejów, Poland." Palaeogeography, Palaeoclimatology, Palaeoecology 370 (2013): 145-157.
- ^ Mateus, O., Butler R. J., Brusatte S. L., Whiteside J. H., & Steyer S. J. (2014). The first phytosaur (Diapsida, Archosauriformes) from the Late Triassic of the Iberian Peninsula. Journal of Vertebrate Paleontology. 34(4), 970-975
Further reading
- Sengupta, D. P. (2002). Indian metoposaurid amphibians revised. Paleontological Research, 6(1), 41-65.
External links
- Wrong number of fingers leads down wrong track, on: EurekAlert!. Source: News Release 24-Jul-2020, University of Bonn