Paleonews: Dinosaurs Were Mostly Scaly

tyrannosaurus_rexFor over a century, the debate about how what dinosaurs truly looked like has raged. In that time, and owing to a poverty of hard evidence beyond fossilized bones, paleontologists have produced some rather wild theories. Whereas some have stuck to the notion that dinosaurs were scaly, others have suggested everything from flat-skin to fur to feathers. And now, it seems that a clear picture may have emerged.

After surveying all the world’s known fossils of dinosaur skin, a pair of paleontologists says the vast majority of non-avian dinosaurs were scaly-skinned, much like reptiles. While the case for certain species of theropods – that gave rise to modern avians – having feathers remains strong, it now seems that these were the exception and not the rule, as some previously thought.

dinosaur_featheredUp until now, opinion remained divided because of the feather-like skin impressions that were found around the fossilized remains of certain theropods, the dinosaur group that contained the likes of Tyrannosaurus and Velociraptor. By contrast, the ornithischian lineage — i.e. Triceratops, Stegosaurus, Ankylosaurus, etc. — and the huge, long-necked sauropod’s were considered to be scaly.

However, the discovery, beginning in 2002, of a few ornithischians with filament-like structures in their skin. This led to speculation that feather-like structures were an ancestral trait for all dinosaur groups. Keen to know more, palaeontologists Paul Barrett of the Natural History Museum in London and David Evans of the Royal Ontario Museum in Toronto created a database of all known impressions of dinosaur skin tissues.

paul_barretAfter compiling the data, they then proceeded to identify those that had feathers or feather-like structures, and considered relationships in the dinosaurian family tree. The results, which were revealed back in October at the annual meeting of the Society of Vertebrate Palaeontology, indicate that although some ornithischians had quills or filaments in their skin, the overwhelming majority had scales.

In addition, the survey results suggest that dinosaur feathers, bristles, or fuzz did not arise early enough in the family tree to spread to many non-avian dinosaurs. According to Richard Butler, a paleontologist from the University of Birmingham in the U.K who was not associated with the study, the results are a “valuable reality check” about the appearance of early dinosaurs.

dinosaur_skinEven so, during an interview with Nature News, Butler was quick to points out that the findings are not set in stone:

We don’t have primitive dinosaurs from the late Triassic and early Jurassic periods preserved in the right conditions for us to find skin or feather impressions. This picture could quickly change if we start finding early dinosaurs with feathers on them.

As a result, paleontologist cannot be precisely sure when or how dino-feathers evolved. If they arose further back in the dinosaur family tree, then more dinosaurs are likely have them. And with new discoveries being made all the time, things may once again tip back in favor of the majority of dinosaurs being feathered, furry or fuzzy.


Paleonews: Reconstructing what Dinosaurs Looked Like

dinosaur_bonesSince the first discovery of their remains was made, modern humans have struggled to reconstruct how dinosaurs lived, behaved, and even appeared. As simple as it may seem to the rest of us, paleontologists understand that bones alone do not an accurate representation make. And over the years, many theories have been advanced as to what the full, fleshy forms of dinosaurs truly looked like.

And thanks to a find made in Grand Prairie, Alberta last year, one of the richest source of dinosaur bones in the world, scientists are that much closer to getting an accurate picture as to what one candidate – Edmontosaurus regalis – looked like. In short, the find revealed a body part never seen before on any dinosaur –  a soft, fleshy comb on its head, similar to those found on roosters.

edmontosaurus-regalisAccording to Victoria Arbour, a University of Alberta paleontologist who co-authored the scientific paper published Thursday in the journal Current Biology, the comb constituted a “structure that was completely unexpected.” And that it “kind of makes us wonder what other dinosaurs might have had.” The find is also interesting because of the connection it draws to the biology of today’s animals, something which is still considered distinct from prehistoric creatures.

Edmontosaurus are a duck-billed, plant-eating dinosaur that grew to be 12 metres long and was thought to have roamed North America in herds during the late Cretaceous, about 75 and 65 million years ago. It also belonged to a group of dinosaurs known as hadrosaurs, a family of duck-billed herbivores which were the most common dinosaurs on the continent at the time.

edmontosaurusPhil Bell, a paleontologist at the University of New England in Armidale, Australia, was with the Philip J. Currie Dinosaur Museum currently under construction in Grand Prairie, Alta., when he uncovered the fossil last summer with geologist Federico Fanti of the University of Bologna. As the lead author of the paper, Bell claims that the new findings are a major breakthrough in determining the dinosaur’s behavior.

In particular, the existence of the comb adds to evidence that Edmontosaurus was a social animal, as ornaments like combs and crests are typically used for communication among animals such as roosters, especially in relation to competition for females:

[E]quivalent to discovering for the first time that elephants had trunks. These findings dramatically alter our perception of the appearance and behaviour of this well-known dinosaur. We might imagine a pair of  male Edmontosaurus sizing each other up, bellowing, and showing off their head gear to see who was the dominant male and who is in charge of the herd.

dinosaur_fossilsAnd of course, this find demonstrates many of the limitations imposed on paleontologist, as fossils typically only preserve the bones of an animal and not fleshy structures. But in rare cases, fossils are found that are described as “mummified”, where bones are in the same positions relative to each other that they would have been in life, with impressions of the skin preserved on top.

According to Arbour, it’s not clear what conditions lead the preservation of skin impressions, but it likely involves the animals dying in a flood and being quickly buried by sand or mud. She added that even when skin impressions are preserved, they are often only visible in certain lighting or when the rock breaks a certain way, which may be why combs hadn’t been noticed on earlier “mummified” Edmontosaurus fossils.

dinosaur_skinimpressionsWhile earlier hadrosaurs had bony crests, researchers thought the crest had been completely lost in Edmontosaurus. The new discovery suggests that, in fact, the dinosaurs’ crests had changed, but remained an important feature. Bell said it also suggests that similar structures may have been missed in other dinosaurs:

There’s no reason that other strange fleshy structures couldn’t have been present on a whole range of other dinosaurs, including T. rex or Triceratops.

So really, this single find could have far-reaching implications for the field of paleontology. And with time, more discoveries, and additional refinements to the excavation process, we might just get a full and complete picture of what life really and truly looked like on Earth millions of years ago.