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| Minmi under attack A theropod assaults a young Minmi as older animals
move in to drive it off. Predators like Kakuru preyed on the young, despite the protective
armour that even covered their bellies. |
Minmi was the first
armoured ornithischian to be found in the Southern Hemisphere. It is named after Minmi
Crossing, a place near the site in Queensland, Australia where the first skeleton was
found. This herbivore has two peculiar features: bony rods grew backwards from unique,
flat bony plates beside the neural spines of the dorsal vertebrae; and a mosaic of small
scutes (bony plates) protected the belly. Minmi's classification is still uncertain. First
placed in the nodosaurid family, it might prove to be a primitive ankylosaurid, or even
part of a new, third family of armoured dinosaurs.
Minmi was a four-legged, armoured
herbivore that stomped around on all four sturdy limbs, cutting off leafy fronds with its
beak and chewing them between its small, leaf - shaped cheek teeth. Its body was thickly
covered with armour that would have discouraged attack. Even a theropod that succeeded in
overturning a Minmi risked snapping off its teeth against the belly armour.
The whole underside appears to have
been covered with small, rounded scutes (bony plates) slightly over 5mm (about 1/4in) in
diameter. It is possible that Minmi may have preferred running to passive resistance. This
may have been facilitated by Minmi's most remarkable feature, which was not found in any
other known ankylosaur. Beside each dorsal (back) vertebra there was a bony plate, known
as a paravertebra, some 2cm (1/4in) long by 4cm (1 1/2in) wide. Attached to this was a rod
of bone, which was similar to the bony tendons found in ornithopods. The rods might have
reinforced the spine and eased the strain on it when the clumsy animal pounded the ground
as it ran.
Two fossil skeletons have been
discovered, both in Australia. The animals seem to have lived in open woodland, and both
specimens seem to have been washed out to sea by rivers when they died, settling upside
down on the seabed. Clay filled the body cavities, and then hard marine sediments encased
the carcasses. Later still, the sea retreated to expose the rocks in which the fossils lay
entombed.
Location: Australia
Diet: Low-growing plants
Size: Length 3m
Classification:
Family unknown
Infraorder Ankylosauria
Suborder Thyreophora
Order Ornithischia
Time (million years ago): 119-113
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