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Mekosuchus

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Mekosuchus was a genus of extinct crocodilians that lived throughout Australasia. Unlike the long, flat-snouted crocodiles we see today, these animals were primarily terrestrial, meaning they lived on land. They were characterized by short, blunt-snouted heads, known as brachycephalic or altirostral skulls, and strong limbs for walking.

Mekosuchus spp
Mekosuchus spp

This genus was highly successful and widespread, existing from the Oligocene and Miocene epochs. They were part of a diverse group of mekosuchines that included various hunters, such as semi-aquatic ambush predators and long-snouted fish eaters.

Mekosuchus inexpectans
Mekosuchus inexpectans

The anatomy of Mekosuchus shows how these animals adapted to different lifestyles. For example, M. whitehunterensis possessed blade-like teeth and specialized neck vertebrae. These bones suggest the animal had powerful epaxial neck muscles, which are the muscles running along the spine. This anatomy likely allowed for violent side-to-side thrashing to strip flesh from carcasses.

Mekosuchus Australia
Mekosuchus Australia

In contrast, M. inexpectatus had bulbous posterior teeth in the back of its mouth. These teeth were likely used to crack the hard shells of molluscs or crustaceans, such as snails.

Some researchers even suggest these animals were nocturnal, living near rainforest streams at night.

Scientists recognize four distinct species within the Mekosuchus genus. M. whitehunterensis is the oldest known species, dating back to the Late Oligocene in Queensland, Australia. M. sanderi is another species found on the Australian mainland in the Riversleigh World Heritage Area. The third species, M. inexpectatus, is the type species and was found on the island of New Caledonia.

Mekosuchus inexpectatus mandible
Mekosuchus inexpectatus mandible

The fourth and youngest confirmed species is M. kalpokasi, found on the island of Éfaté in Vanuatu. Because the remains of M. kalpokasi are very fragmentary, some researchers suggest it might actually be the same as M. inexpectatus.

The history of these fossils began in 1981 with the collection of a single bone in Kanumera Bay, New Caledonia. Eric Buffetaut first reported these findings in 1983. Later, in 1987, Buffetaut and Jean-Christophe Balouet provided a formal description of the animal. The name Mekosuchus combines "Mek," the Drehu name for Grande Terre, with the suffix "-suchus," which means crocodile.

Mekosuchus Australia
Mekosuchus Australia

Later, in 1997, Paul Willis described M. whitehunterensis, marking the first time a species was found on the Australian mainland rather than an island.

Detailed studies of the skull reveal unique features that separate Mekosuchus from modern crocodiles. Their eye sockets, or orbits, were large and partially formed by the maxilla, which is the upper jaw bone. This prevented the jugal and lacrimal bones from touching. The tooth rows also showed a pattern called festooning, where the teeth sit in a wave-like arrangement.

Mekosuchus spp
Mekosuchus spp

This wave-like pattern was very prominent in the short-snouted species. Other differences between species include the size of the palatal fenestrae, which are openings in the roof of the mouth, and the length of the mandibular symphysis, the fused part of the lower jaw.

Estimating when Mekosuchus disappeared is a complex task for paleontologists. The genus likely went extinct during the Holocene, approximately 3,000 years ago. However, some radiocarbon dating of M. inexpectatus fossils from the Pindai Caves suggests they may have survived as recently as 1,720 years ago.

Mekosuchus inexpectatus mandible
Mekosuchus inexpectatus mandible

There is debate regarding whether they survived into human times. While some researchers suggest humans might have caused their extinction, there are no direct signs of human involvement found in the fossil record. The exact cause of their disappearance remains unknown.

The study of Mekosuchus connects many different fields of science. It involves paleontology to study the fossils and geology to understand the age of the rock layers. It also touches on island biogeography, which looks at how animals live on isolated landmasses. By studying these extinct crocodilians, scientists gain a better understanding of how diverse reptile groups evolved and moved across the ancient landscapes of Australasia.

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🖼️ Images & Media (5)
File:Mekosuchus Australia.jpg
Mekosuchus Australia.jpg
File:Mekosuchus spp.png
Mekosuchus spp.png
File:Mekosuchus inexpectatus mandible.JPG
Mekosuchus inexpectatus mandible.JPG
File:Mekosuchus inexpectans.JPG
Mekosuchus inexpectans.JPG
File:Placostylus fibratus Martyn, 1789 (4192730777).jpg
Placostylus fibratus Martyn, 1789 (4192730777).jpg
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