Metriorhynchus
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| iMetriorhynchus
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Extinct (fossil)
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| Metriorhynchus | |
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| Type | marine crocodylian |
| Length | 2.4-6 m |
| Movement | swimming |
| Diet | carnivore |
| Environment | ocean |
| Distribution | England, France, Switzerland, Argentina and Chile |
Metriorhynchus was a marine crocodyliform that lived in the oceans during the Middle to Late Jurassic Period. Metriorhynchus was a carnivore that spent much, if not all, its life out at sea. No Metriorhynchus eggs or nest have been discovered, so little is known of the reptile's lifecycle, unlike other large marine reptiles of the Mesozoic, such as plesiosaurs or ichthyosaurs which are known to give birth to live young out at sea. Where Metriorhynchus mated, whether on land or at sea, is currently unknown.
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[edit] Species
The species within Metriorhynchus include : the type species M. geoffroyii, M. hastifer, M. acutus and M. palpebrosus from Western Europe of the Late Jurassic. M. superciliosus, M. brachyrhynchus and M. leedsi from Western Europe of the Middle Jurassic. M. casamiquelai from Chile of the Middle Jurassic and M. potens from the End Jurassic of Argentina.
[edit] Size and Form
Averaging around three metres in length, Metriorhynchus is compared to living crocodilians medium-sized, though size estimates for Metriorhynchus suggest it could grow to at least the size of modern saltwater crocodiles. Its body was streamlined for greater hydrodynamic swimming, which along with its finned tail made it a more efficient swimmer than modern crocodilian species.
[edit] Diet and Behavior
Metriorhynchus was a versatile and opportunistic predator, predated upon both the armoured belemnites, fast moving fish and the giant filter feeding fish Leedsichthys. Occasionally it was also capable of capturing flying animals such as the pterosaurs and scavenging on plesiosaur carcassess on the sea-floor.
[edit] Predators
Even though Metriorhynchus was an effective predator, it was vulnerable to predation from super predators such as Liopleurodon which could grow in excess of 10 metres in length. Since Metriorhynchus had lost its osteoderms, "armour scutes", to become more efficient swimmers it would have had little defence against larger marine predators.
[edit] Closely related species
Metriorhynchus is the type genus for the Metriorhynchidae. Other genera included in this family are: Teleidosaurus, Geosaurus, Dakosaurus and Enaliosuchus. The genera within Metiorhynchidae considered nomen dubium are Aggiosaurus and Neustosaurus.
[edit] Geological Ages
Metriorhynchus is known from the Bajocian, Bathonian and Callovian of the Middle Jurassic and from the Oxfordian stage, Kimmeridgian and Tithonian of the Late Jurassic.
[edit] References
- Adams-Tresman, S.M. (1987). The Callovian (Middle Jurassic) marine crocodile Metriorhynchus from Central England. Palaeontology 30 (1): 179-194
- Buffetaut, E. (1982). Radiation évolutive, paléoécologie et biogéographie des Crocodiliens mésosuchienes. Mémoires Societé Geologique de France 142: 1–88
- Forrest, R. (2003). Evidence for scavenging by the marine crocodile Metriorhynchus on the carcass of a plesiosaur. Proceedings of the Geologists’ Association 114: 363-366
