Name:
Metriorhynchus
(Moderate snout).
Phonetic: Met-ree-oh-rink-us.
Named By: Christian Erich Hermann von Meyer -
1830.
Synonyms: Suchodus.
Classification: Chordata, Sauropsida,
Mesoeucrocodylia, Thalattosuchia, Metriorhynchidae.
Species: M. brevirostris (type).
Type: Carnivore.
Size: 3 meters long.
Known locations: Europe.
Time period: Callovian through to Kimmeridgian of
the Jurassic.
Fossil representation: Many known specimens.
Metriorhynchus
is one of the
better known marine
crocodiles with features that show it was more at home in the water
than on the land. The legs have evolved to become more like
flippers, and the tail sports evidence of a tail fluke. It is
likely that the tail provided primary locomotion in the water with the
legs being used for maneouvering.
One
strong piece of evidence to suggest that Metriorhynchus
spent most of
its life in the water is the presence of salt glands. These salt
glands are found in many marine animals and work by extracting excess
salts from the blood so that they can be excreted externally in a
concentrated form. By having an active gland constantly removing salt
from the blood, marine creatures, including Metriorhynchus
would
have been able to drink seawater as well as eat other marine animals
that would have had a higher salt content than land animals.
It
is not known for certain if Metriorhynchus spent
all of its time in the
water or if it returned to the land. On land Metriorhynchus
would
have certainly been more cumbersome, as evidenced by its marine
specialisations, but it may have had too for special tasks such as
laying eggs, just like turtles have too. While other marine
reptiles like icthyosaurs almost certainly gave birth to live young,
it needs to be remembered that these evolved from different lines,
and that Metriorhynchus had more immediate
terrestrial ancestors,
meaning that it may not have had enough evolutionary time to develop
live birth at sea.
Although
an active predator in its own right, there is also evidence for
Metriorhynchus scavenging on animals like
plesiosaurs, indicating an
opportunistic lifestyle. In turn, Metriorhynchus
may have been
preyed upon by larger predators such as the short necked pliosaurs
such as Pliosaurus
and Liopleurodon.
that
swam the oceans at the same time. Other well known Mesozoic marine
crocodiles include Geosaurus
, Torvoneustes,
Plesiosuchus
and Dakosaurus.
Further reading
- Achte Versammlung der Naturforscher und Aerzte zu Heidelberg im
September 1829. - Isis von Oken, 1830: 517-519. - H. von Meyer - 1830.
- M�moire sur les dinosauriens et les crocodiliens des terrains
jurassiques de Boulogne-sur-Mer [Memoir on the dinosaurs and
crocodilians of the Jurassic deposits of Boulogne-sur-mer]. - M�moires
de la Soci�t� G�ologique de France, s�rie 2 10(2):1-57. - H. -E.
Sauvage - 1874.
- On a crocodilian jaw from the Oxford Clay of Peterborough. -
Quarterly Journal of the Geological Society of London 46:284-288. - R.
Lydekker - 1890.
- The Mesozoic reptiles of Dorset. Part one. - Proceedings of the
Dorset Natural History and Archaeological Society 79:47-72. - J. B.
Delair - 1958.
- Un nuevo cocodrilo marino (Crocodylia, Metriorhynchidae) del
Caloviano del norte de Chile. [A new marine crocodile (Crocodylia,
Metriorhynchidae) of Callovian of northern Chile.]. - Ameghiniana
17(2):97-10. - Z. B. Gasparini - 1980.
- Radiation �volutive, pal�o�cologie et biog�ographie des Crocodiliens
m�sosuchienes. [Adaptive radiation, paleoecology and biogeography of
crocodiles m�sosuchienes] - M�moires Societ� Geologique de France 142:
1–88. - E. Buffetaut - 1982.
- The Callovian (Middle Jurassic) marine crocodile Metriorhynchus
from
Central England. - Palaeontology 30 (1): 179-194. - S. M. Adams-Tresman
- 1987.
- Swimming capabilities of Mesozoic marine reptiles; implications for
method of predation. - Paleobiology 14 (2):187-205. - J. A. Massare -
1988.
- Evidence for scavenging by the marine crocodile Metriorhynchus
on the
carcass of a plesiosaur. - Proceedings of the Geologists’ Association
114: 363-366. - R. Forrest - 2003.
- Salt glands in the fossil crocodile Metriorhynchus. - Journal of
Vertebrate Paleontology 26 (4): 1009-1010. - R. Gandola, E. Buffetaut,
N. Monaghan, G. Dyke - 2006.
- Salt glands in the Jurassic metriorhynchid Geosaurus:
implications
for the evolution of osmoregulation in Mesozoic crocodyliforms. -
Naturwissenschaften 95: 79-84. - 2008.
- Un nuevo esp�cimen de cocodrilo marino del Jur�sico Medio del norte
de Chile: revalidaci�n de Metriorhynchus westermanni
(Crocodyliformes:
Metriorhynchidae). [A new specimen of marine crocodile from the Middle
Jurassic of northern Chile: revalidation Metriorhynchus
westermanni
(Crocodyliformes: Metriorhynchidae).] - Revista Geologica de Chile
35(2):335-346. - Z. Gasparini, A. Paulina-Carabajal & G. Chong
- 2008.
- The evolution of Metriorhynchoidea (Mesoeucrocodylia,
Thalattosuchia): an integrated approach using geometrics morphometrics,
analysis of disparity and biomechanics. - Zoological Journal of the
Linnean Society 158: 801-859. - Mark T. Young, Stephen L. Brusatte, M.
Ruta & Marco B. Andrade - 2009.
- The evolution of Metriorhynchoidea (Mesoeucrocodylia,
Thalattosuchia): an integrated approach using geometric morphometrics,
analysis of disparity, and biomechanics. - Zoological Journal of the
Linnean Society 158(4):801-859. - M. T. Young, S. L. Brusatte, M. Ruta
& M. B. Andrade - 2010.
- A new metriorhynchid crocodylomorph from the Lower Kimmeridge Clay
Formation (Late Jurassic of England), with implications for the
evolution of dermatocranium ornamentation in Geosaurini. - Zoological
Journal of the Linnean Society 169:820-848. - M. T. Young, M. B. de
Andrade, S. Etches & B. L. Beatty - 2013.
- Filling the Corallian gap: New information on Late Jurassic marine
reptile faunas from England. - Acta Palaeontologica Polonica 63 (2):
287–313. - D. Foffa, M. T. Young & S. L. Brusatte - 2018.
- Cutting the Gordian knot: a historical and taxonomic revision of the
Jurassic crocodylomorph Metriorhynchus. -
Zoological Journal of the
Linnean Society, zlaa092. - Mark T. Young, Arnaud Brignon, Sven Sachs,
Jahn J. Hornung, Davide Foffa, James J. N. Kitson, Michela M. Johnson
& Lorna Steel - 2020.