Killer Dino 'Turned Vegetarian'

[Dorsk 81]

A "mass graveyard" of bird-like dinosaurs has been uncovered in Utah, US, Nature magazine reports this week.

Scientists believe the previously unknown species was in the process of converting to vegetarianism from a rather more bloodthirsty diet.

Falcarius utahensis seems to represent an intermediate stage between a carnivorous and herbivorous form.

The creature, which lived in the Early Cretaceous Period, provides a "missing link" in dinosaur evolution.

"Falcarius represents evolution caught in the act, a primitive form that shares much in common with its carnivorous kin, while possessing a variety of features demonstrating that it had embarked on the path toward more advanced plant-eating forms," said co-author Scott Sampson of the Utah Museum of Natural History.

Falcarius utahensis belonged to a group of dinosaurs known as therizinosaurs, which were cousins of Velociraptors and the early ancestors of birds.

The bizarre creature appears to sit halfway between nippy carnivores and later, lumbering plant-eating therizinosaurs, although scientists cannot be entirely sure what it ate itself.

"Falcarius shows the beginning of features we associate with plant-eating dinosaurs, including a reduction in size of meat-cutting teeth to leaf-shredding teeth, the expansion of the gut to a size needed to ferment plants and the early stages of changing the legs so they could carry a bulky body instead of running fast after prey," said James Kirkland of the Utah Geological Survey.

Ferocious past

The adult dinosaur walked on two legs, was about 4m-long (13ft) and stood 1.4m-tall (4.5ft). It also had a woolly feather-like plumage and sharp, curved 10cm-long (4-inch) claws.

These formidable talons were probably a hang-over from the dinosaur's ferocious past, the researchers say, and may not have had a function in its more sedate new lifestyle.

Falcarius shared an - as yet undiscovered - ancestor with the Velociraptor, which was almost certainly a fleet-footed, small bodied predator, the researchers believe.

At some point, two major groups of dinosaurs split from their carnivorous cousins and shifted into plant-eating. But until now, the intermediate stages of this process remained a mystery.

"With Falcarius, we have actual fossil evidence of a major dietary shift, certainly the best example documented among dinosaurs," said Dr Sampson.

"This little beast is the missing link between small-bodied predatory dinosaurs and the highly specialised and bizarre plant-eating therizinosaurs."

Although the team cannot know whether Falcarius was a committed vegetarian - it may have eaten a bit of meat too - its emergence did coincide neatly with the evolution of flowering plants.

"At the same time Falcarius appeared, the world was changing greatly because flowering plants were appearing," Dr Sampson said. "They would have provided a new food source. It could be that Falcarius was exploiting an open ecological niche."

Mass grave

Researchers were able to get such a complete idea of what Falcarius looked like, because they were lucky enough to find a "mass grave" of the species at the base of the Cedar Mountain rock formation, south of Green River in Utah.

James Kirkland estimates hundreds to thousands of individual dinosaurs - from hatchlings to adults - died at the 8000 sq m dig site.

No one knows quite what killed them, but mass deaths have appeared in the fossil record before. Scientists have suggested drought, volcanism, fire and botulism poisoning as possible causes.

"Mass mortalities are known in a number of dinosaur groups," said Dr Sampson. "In this case it is difficult to work out what happened. It could have been a spring which dried up, and the dinosaurs died of thirst.

"Or organic poisons could have contaminated the water - it is hard to know for sure."

[LadyTevar]

Could it have been a flashflood? Or maybe the sudden escape of toxic gas?

[Chmee]

Falcarius utahensis seems to represent an intermediate stage between a carnivorous and herbivorous form.

Impossible! As every good fundie knows, there is no such thing as 'transitional' evidence in the fossil record!

Washington Post coverage

[Ender]

More imjportantly, doesn't this serve as evidence towards them evolving into birds? I mean, precious few birds eat meat, most nuts and other plant matter.

Or are the teeth too different and this was solid herbivore?

[Darth Raptor]

Could it have been a flashflood? Or maybe the sudden escape of toxic gas?

Since this is early Cretaceous Utah, probably the former.

More imjportantly, doesn't this serve as evidence towards them evolving into birds? I mean, precious few birds eat meat, most nuts and other plant matter.

Or are the teeth too different and this was solid herbivore?

Not really, birds are pretty far-removed from the therazinosaurid line. This is important becaue it's (gasp!) an obvious "transitional form" and the earliest known species of therazinosaur. There are plenty of carnivorous birds, teeth have little to do with it.

Since this pegs the divergence of the Therazinosauridae at about the same time that flowering plants evolved, this lends credence to the theory that they evolved to prey on social insects like wasps and termites. The big foreclaws would have been perfect for ripping open mounds. What I think is wierd is that this turned up in North America instead of Asia. The family must have migrated literally as they evolved.

[wolveraptor]

I've always wondered how the transition actually went? How did carnivorous guts learn to deal with tough plant matter? The same thing had to have happened in the Mid-Triassic, because the first dinos were puny carnivorous theropods. How did they first start to injest plant matter? What were the first plants they ate. Perhaps ancestors of Falcarius lived like dogs: mostly predatory, but willing to eat berries and grass. But it still leaves the question of when dogs began to be omnivorous. Most likely, it traces all the way back to the beginning of their ancestry of small, scurrying mammals. But when did they become omnivores? Their direct ancestors, the cynodonts, were carnivorous. Were they forced into omnivory by competition from archosaurs? Even then, what physiological changes took place?

LadyTevar wrote:

Could it have been a flashflood? Or maybe the sudden escape of toxic gas?

Since this is early Cretaceous Utah, probably the former.

Actually, Kirkland, according to the Washington Post, favors poison, or

...some kind of microbial bloom...

For me, this explains the nece

[InnerBrat]

*grins* *coughs*

Why, look at where it was discovered! I wonder if anyone we know was involved in that dig...

*beams*

OK, sorry.

[Shroom Man 777]

That's just so cool (being involved in a noteworthy dino dig, I mean).

[wolveraptor]

I've always wondered how the transition actually went? How did carnivorous guts learn to deal with tough plant matter? The same thing had to have happened in the Mid-Triassic, because the first dinos were puny carnivorous theropods. How did they first start to injest plant matter? What were the first plants they ate. Perhaps ancestors of Falcarius lived like dogs: mostly predatory, but willing to eat berries and grass. But it still leaves the question of when dogs began to be omnivorous. Most likely, it traces all the way back to the beginning of their ancestry of small, scurrying mammals. But when did they become omnivores? Their direct ancestors, the cynodonts, were carnivorous. Were they forced into omnivory by competition from archosaurs? Even then, what physiological changes took place?

LadyTevar wrote:

Could it have been a flashflood? Or maybe the sudden escape of toxic gas?

Since this is early Cretaceous Utah, probably the former.

Actually, Kirkland, according to the Washington Post, favors poison, or

...some kind of microbial bloom...

For me, this explains the nece

...ack! What was I going to say? Shit, man, I hate it when this happens. Traling off in the middle of an effing post...

[Rye]

*grins* *coughs*

Why, look at where it was discovered! I wonder if anyone we know was involved in that dig...

*beams*

OK, sorry.

I was just going to mention you when I read the other thread about this, I only just get round to this one and see you've already crushed my dreams like so much sedimentary rock under geological pressure.

[LadyTevar]

*grins* *coughs*

Why, look at where it was discovered! I wonder if anyone we know was involved in that dig...

*beams*

OK, sorry.

You were in on it! Sweeeeeeeeet!

[Shroom Man 777]

Yeah. And this isn't like your average carnosaur, this is them therozinosaurs. The weirder less understood ones.

[wolveraptor]

*grins* *coughs*

Why, look at where it was discovered! I wonder if anyone we know was involved in that dig...

*beams*

OK, sorry.

You were in on it! Sweeeeeeeeet!

So? How much for the fossil? I say we start the bidding at 1000 dollars.

[DPDarkPrimus]

Do you have any photos of the fossils, IB? That would be totally awesome....

[wolveraptor]

If it gets put in a museum, and you get to decide the pose, base it off Sue: she looks so fucking cool, leaning slightly forward, her knees tensed, almost alive (except for the fossilization part). She looks right down at people who stand right in front of her. It's almost orgasmic.

[HemlockGrey]

No doubt they also abstained from alcohol.

[InnerBrat]

Pics from the dig can indeed be found here.

Of course, I find out about this because my supervisor was contacted by the museuem's press office, but he recommneded me.

[Lord Zentei]

The CNN article: (Link)

With pic:

[wolveraptor]

Man, who draws those things?

[Elfdart]

Pandas are descended from carnivores who took up eating bamboo instead of meat. Why is this surprising?

Look at the family tree of Andrewsarchus which goes back and forth between plant and meat eating.

[InnerBrat]

Pandas are descended from carnivores who took up eating bamboo instead of meat. Why is this surprising?

Look at the family tree of Andrewsarchus which goes back and forth between plant and meat eating.

The fact of evolution of a herbivore isn't surprising. All herbivores had a carnivorous ancestory, carnivory being the primitve state in most lineages.

The discovery of a transitional form between the two states is, however, significant.

[Shroom Man 777]

Pandas are descended from carnivores who took up eating bamboo instead of meat. Why is this surprising?

Look at the family tree of Andrewsarchus which goes back and forth between plant and meat eating.

Bears, the Panda's ancestors, were omnivorse. They also ate nuts and berries, as well as ox testicles. Just nitpicking.

[Elfdart]

Pandas are descended from carnivores who took up eating bamboo instead of meat. Why is this surprising?

Look at the family tree of Andrewsarchus which goes back and forth between plant and meat eating.

Bears, the Panda's ancestors, were omnivorse. They also ate nuts and berries, as well as ox testicles. Just nitpicking.

"Carnivore" refers to mammals with carnassial teeth (the front molars) that form scissors for cutting meat. I was referring to the earliest bears and bear-dogs, which were exclusively meat eaters. It was later on that their rear molars flattened out (cats lost them entirely and hyenas developed "bolt-cutter" molars), allowing them to chew plants and other things.

[wolveraptor]

IIRC the orginal members of Canoidea never lost the omnivory inherited from their small, rat-like ancestors. Even the predatory species were slightly omnivorous, like modern dogs and wolves.

[wolveraptor]

EDIT: mustelids and pinnepeds (sp?) became exclusively carnivorous.