Name:
Metoposaurus
(Front lizard).
Phonetic: Me-top-o-sore-us.
Named By: Richard Lydekker - 1890.
Synonyms: Metopias, Metoposaurus heimi,
Metoposaurus stuttgartiensis, Trigonosternum
Classification: Chordata, Amphibia,
Temnospondyli, Stereospondyli, Metoposauridae.
Species: M. diagnosticus diagnosticus
(type), M. algarvensis, M. diagnosticus krasiejowensi,
M.
maleriensis, M. ultimus. The additional species
M. azerouali, M. fraasi, M. jonesi and M.
santaecruci are sometimes mentioned, thought these are not
considered valid by all.
Diet: Carnivore/Picivore.
Size: Up to 3 meters long.
Known locations: Across Europe including France -
Gres � Avicula contorta Formation (Lorraine), Germany -
L�wenstein Formation, Stuttgart Formation, Weser Formation
(Baden-W�rttemberg and Bayern for Stuttgart Formation), Hassberge
Formation (Bayern), Trossingen Formation (Sachsen-Anhalt),
Italy - Raibl Beds Formation (Bolzano) and Poland - Drawno
Beds Formation (Opole), as well as Canada - Wolfville
Formation (Nova Scotia), USA - Santa Rosa Sandstone Formation
and Dockum Formation (both Texas). Possibly also India - Tiki
Formation (Madhya Pradesh).
Time period: Carnian to Rhaetian of the Triassic.
Fossil representation: Remains of multiple
individuals.
The
genus Metoposaurus was originally named as Metopias
by Christian von
Meyer in 1842, but the name was replaced and changed to
Metoposaurus by Richard Lydekker in 1890. Metoposaurus
is the type
species of the Metoposauridae, a group of temnospondyl amphibians
that are particularly noted for having eyes that are placed further
forward on the head. Relatives of Metoposaurus
include Apachesaurus,
Bogdania, Dutuitosaurus and Anaschisma.
Like
relative genera, Metoposaurus lived during the
closing stages of the
Triassic, and shows developments that best support a primarily if not
an entirely aquatic lifestyle. Most obvious is the limb reduction,
with the legs seemingly not large of strong enough to lift the body
clear off the ground if an individual Metoposaurus
found itself out of
the water. The shape of the skull is also quite flat on top which
means that a Metoposaurus near the surface of the
water would not
expose itself that much to anything that was on the surface. Grooves
in the skull also hint at the presence of a sensory system similar to
the lateral line of a fish which would have detected changes in water
pressure caused by the movement of nearby animals. The latter
development is not unique to the metoposaurid however since similar
adaptations can also be seen on other genera such as Mastodonsaurus,
though again this genus is widely believed to have been entirely
aquatic. Another piece of evidence that supports an entirely aquatic
lifestyle is the discovery of several Metoposaurus
clustered together
in what is thought to have been a dried out body of water, an
occurrence which has also been seen in other related genera.
Further reading
- Species discrimination of the Late Triassic temnospondyl amphibian
Metoposaurus diagnosticus. - Acta Palaeontologica
Polonica. 47:
535–546. - T. Sulej - 2002.
- Osteology, variability, and evolution of Metoposaurus,
a temnospondyl
from the Late Triassic of Poland. - Palaeontologica Polonica. 64:
29–139. - T. Sulej - 2007.
- A new metoposaurid (temnospondyl) bonebed from the Late
Triassic of Portugal - J. S. Steyer, O. Mateus, R. J.
Butler, S. L. Brusatte & J. H. Whiteside -
2011.
Unique growth pattern of Metoposaurus diagnosticus
krasiejowensis
(Amphibia, Temnospondyli) from the Upper Triassic of Krasiej�w, Poland.
- Palaeogeography, Palaeoclimatology, Palaeoecology 370 (2013):
145-157. - Dorota Konietzko-Meier & Nicole Klein - 2013.
- A new species of Metoposaurus from the Late
Triassic of Portugal and
comments on the systematics and biogeography of metoposaurid
temnospondyls. - Journal of Vertebrate Paleontology. 35: e912988. - S.
L. Brusatte, R. J. Butler, O. Mateus & S. J. Steyer - 2015.
- Ornamentation of dermal bones of Metoposaurus krasiejowensis
and its
ecological implications. - PeerJ. 6: e5267. - M. Antczak & A.
Bodzioch - 2018.
- Redescription of Arganasaurus (Metoposaurus) azerouali (Dutuit) comb.
nov. from the Upper Triassic of the Argana Basin (Morocco), and the
first phylogenetic analysis of the Metoposauridae (Amphibia,
Temnospondyli). - Papers in Palaeontology. - Valentin Buffa,
Nour-Eddine Jalil & J.Sebastien Steyer - 2019.