Anaschisma
Name:
Anaschisma.
Phonetic: An-ah-schis-mah.
Named By: Branson – 1905.
Synonyms: Anaschisma brachygnatha,
Borborophagus, Buettneria bakeri, Buettneria perfecta,
Koskinonodon, Metoposaurus bakeri.
Classification: Chordata, Amphibia,
Temnospondyli, Stereospondyli, Metoposauridae.
Species: A. browni (type).
Diet: Carnivore/Piscivore.
Size: Skull 65 centimetres long. Body length
up to 3 meters.
Known locations: USA - Arizona, New Mexico,
Pennsylvania, Texas & Wyoming.
Time period: Norian of the Triassic.
Fossil representation: Partial remains of numerous
individuals.
Anaschisma
is a genus of temnospondyl amphibian known to have lived in North
America during the late Triassic. Anaschisma were
primarily aquatic
predators using their salamander-like bodies to swim through the water
and navigate submerged obstacles in searching for prey.
Anaschisma
is regarded as a metoposaurid temnospondyl amphibian, which means
that it is closest to genera such as Metoposaurus
and Apachesaurus.
These temnopondyls are noted for having eyes that were situated in a
more forward position on their skulls than the eyes of other similar
temnospondyl groups. Also like its relative genera, Anaschisma
seems to have been more at home in the water where it probably hunted
for fish and possibly other amphibians. The limbs are generally not
that well supported for terrestrial locomotion, and the presence of a
lateral line formed by sensory sulci would have detected changes in
water pressure, allowing them to pick up upon the movements of nearby
swimming animals.
Further
evidence for a mostly aquatic lifestyle can be inferred from
collections of Anaschisma which can be interpreted
as mass graves where
a body of water dried out, leaving many Anaschisma
exposed to the dry
air. The remains of these Anaschisma are found so
close together that
they seem to have clustered together in the last remnants of water
before death. This may have been the result of a body of water not
being replenished by seasonal rain or flood water.
Another
genus of temnospondyl named Koskinonodon is now
often regarded as
synonymous with Anaschisma. This started way back
in 1947, back
when the Anaschisma genus was actually named
Buettneria.
Preoccupation of the name Buettneria, saw the
fossils renamed into a
new genus called Koskinonodon in 2007
(Mueller). A subsequent
re-description of these fossils in 2019 (Gee et al) again came
to the conclusion that they are synonymous with the earlier named
Anaschisma.
Further reading
- Structure and relationships of American Labyrinthodontidae. -
Journal of Geology 13:568-610. - E. B. Branson - 1905.
- Koskinonodon Branson and Mehl, 1929, a
replacement name for the
preoccupied temnospondyl Buettneria Case, 1922. - Journal of
Vertebrate Paleontology. 27 (1): 225. - B. D. Mueller
- 2007.
- Redescription of Anaschisma (Temnospondyli:
Metoposauridae)
from the Late Triassic of Wyoming and the phylogeny of the
Metoposauridae. - Journal of Systematic Palaeontology. 18
(3): 233–258. - Bryan M. Gee, William G. Parker
& Adam D. Marsh - 2019.
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