TrefRex on DeviantArthttps://www.deviantart.com/trefrex/art/Leaellynasaura-amicagraphica-500832273TrefRex

Deviation Actions

TrefRex's avatar

Leaellynasaura amicagraphica

By
Published:
2.9K Views

Description

Named by Tom and Patricia Rich, 1989
Diet: Herbivore (Plants such as ferns and horsetails)
Length: 10 feet (3 meters)
Weight: 200 lb
Region: Victoria Southeastern Australia (Eumeralla Formation)
Age: 118-110 million BC (Late Aptian-Early Albian stage of the Early Cretaceous)
Enemies: Predatory theropods, such as perhaps Timimus, as well as those that were known from fragmentary remains.

We mainly think of dinosaurs as cold-blooded (or ectothermic) animals like modern-day reptiles and live in the warm, lush, tropical regions as large diversities of them were known from. But starting in the 1980's, new discoveries in Australia, Antarctica, and even the North Slope of Alaska show that some dinosaurs not only lived in higher latitudes, but also thrived and survived into some of the coldest and most extreme environments where no other reptiles, such as crocodiles and lizards, can withstand in. It also shows that they were active warm-blooded (or endothermic) animals like birds and mammals.

The first dinosaur to show that adaptation was Leaellynasaura amicagraphica. Discovered by paleontologists Tom and Patricia Rich, in a site called "Dinosaur Cove" on the coastal cliffs of southeastern Victoria in Australia, they named the dinosaur after their daughter Leaellyn Rich.Aww :aww: 

The species name amicagraphica honors the friends of the Museum of Victoria and the National Geographic Society, which funded the research.

Known from several specimens including two nearly complete skeletons and two fragmentary skulls, this boa constrictor-sized animal was an ornithopod. But ranging from formerlly being a hypsilophodont to a primitive ornithischian, or an archaic iguanodontian, exactly what kind of ornithopod dinosaur it belonged remains a dispute.

The unique feature of Leaellynasaura was its tail. It was three times as long as its body, making it among the longest of any ornithischian dinosaur known and it also had more tail vertebrae than any other ornithischians, except for some hadrosaurs. Unlike the tail of more advanced ornithischians, the tail of Leaellynasaura has no ossified tendons in it. This would've allowed it to become flexible enough to move around and may even used their tails to raise up high, possibly used for display, or signalling members of its own species, mainly when threatened.

A fast, agile, bipedal herbivore, it had a horny beak and ridges on its teeth designed to rip up the tough plant matter that it fed on and flees when threatened by predators.

During the time this dinosaur was alive, around 110 million years ago in the Albian stage of the Early Cretaceous period, Australia was stuck to Antarctica, part of the ancient continent of Gondwana, and lay in the Antarctic Circle at a high polar latitude of 75 degrees South. Dinosaur Cove, where it was found, was several hundred miles away from the South Pole and was a floodplain within a great rift valley, formed as Australia was beginning to rip away from Antarctica. There were no polar ice caps back then and instead it was a dense wooded forest of conifers, pines, gingkoes, cycadophytes and ferns and horsetails in the under story. Most of these plants were evergreen and food would've been available for the plant-eating dinosaurs such as Leaellynasaura. The climate was much warmer than it is today, but during winter, there would've been 3 months of total darkness, with temperatures between -6 to + 5 degrees Celsius (21 to 37 degrees Fahrenheit).
Snowy :shivering: v2 brr - sooo c..  c..  c.. cold! Its Cold 

Living alongside Leaellynasaura were other small dinosaurs such as the smaller ornithopod Atlascopcosaurus loadsi and the theropod Timimus hermani (Named after Tom and Pat's son Tim Rich; known from an adult and juvenile legbones; originally an ornithomimosaur, but it is now thought to be a different kind of coelurosaur theropod, possibly a tyrannosauroid), as well as a possible dromaeosaur and oviraptoraptorsaur that are known from fragmentary remains. There were also three distinct genera of small mammals such as Bishop (an australosphenid-a group of Gondwanan mammals that also include the ancestors of today's egg-laying mammals, or monostremes).

But how did the small dinosaurs, like Leaellynasaura, not only thrived, but survived the harsh, cold, dark winters remains a mystery.

In 1996, Anusuya Chinsamy, an expert on microstructure of fossil bones, examined the bone material from both Timimus and Leaellynasaura and discovered different histology. In Timimus, the bone formation had cynical patterns, which suggest that this theropod dinosaur may have hibernated the cold months. In Leaellynasaura, the bone deposition showed a continuous rate, suggesting that it remained active year round. But how Leaellynasaura survived the cold, dark polar winters remains a dispute.

It may have been covered in feathers, or filaments that would've provided warmth, although there is no evidence of it.

But a more intriguing feature of this dinosaur was that the skull fragments of it has been reported to have enlarged eyes and proportionally large optic lobes. This implies an adaptation to low-light conditions, able to see through the darkness of the winter months, searching for food and members of its own kind (though, in recent years, its believed to characteristics of juvenile individuals, instead of low-light adaptation).

Note: As in most Deviant Artworks of this dinosaur, the coloration is based on the Rock Ptarmigan.
Image size
2092x1563px 95.15 KB
© 2014 - 2024 TrefRex
Comments2
Join the community to add your comment. Already a deviant? Log In
Tote-Meistarinn's avatar
Also, -5°C? Lol, that's an exceptionally mild winter over here. We get temperatures of down to -11°C. :P