Freethought & Rationalism Archive

ps418 · 07-08-2003, 12:19 PM

From New Scientist News Service:

Quote:

Remains of the earliest known sauropod, a relative of the largest dinosaurs to roam the Earth, have been unearthed in South Africa.

The new species has been named Antetonitrus ingenipes. Antetonitrus means "before the thunder", marking the species� evolution into the brontosaurus or "thunder lizard" some 65 million years later. It weighed about 2 tonnes. But at 10 to 12 metres long, with a hip height of 2.2 metres, it was dwarfed by its later relatives.

A. ingenipes appears to be the missing link between the sauropods and their mainly two-legged predecessors, the prosauropods. "Its an excellent example of a transitional animal," says Adam Yates, who analysed the bones at the Bernard Price Institute for Palaeontological Research at the University of Witwatersrand in Johannesburg.

Brontosaurus 'missing link' unearthed

The abstract from Yates and Kitching:

Quote:

A partial dinosaur skeleton from the Upper Triassic (Norian) sediments of South Africa is described and named Antetonitrus ingenipes. It provides the first informative look at a basal sauropod that was beginning to show adaptations towards graviportal quadrupedalism such as an elongated forelimb, a modified femoral architecture, a shortened metatarsus and a changed distribution of weight across the foot. These adaptations allowed the clade to produce the largest-ever terrestrial animals. However, A. ingenipes lacked specializations of the hand found in more derived sauropods that indicate it retained the ability to grasp. Antetonitrus is older than the recently described Isanosaurus from Thailand and is the oldest known definitive sauropod.

The earliest known sauropod dinosaur and the first steps towards sauropod locomotion. Proceedings of the Royal Society: Biological Sciences, DOI: 10.1098/rspb.2003.2417.

Patrick

Rhaedas · 07-08-2003, 12:34 PM

I can't wait for the creationists' "yes, but where's the transitional fossils between those fossils and Brontosaurus?" :banghead:

lpetrich · 07-08-2003, 01:20 PM

First, I mean by "leg" a limb used for walking.

Especially interesting here is how sauropods had been descended from two-legged ancestors that had moved back to walking on all fours. This has clearly happened among other herbivorous dinosaurs, like Stegosaurus and the duckbills, where their outsized hind legs give away their two-legged ancestry.

However, the carnivores had stayed two-legged, as have their surviving offshoot, the birds.

The earliest dinosaurs, like Herrerasaurus, had been two-legged, but most legged reptiles have been four-legged, including the closest surviving relatives of the dinosaurs, the crocodilians.

So the four-legged dinosaurs have done:

four-legged -> two-legged -> four-legged
(early reptiles) (early dinosaurs) (some later dinosaurs)

and have gone back to all fours more than once.

Nic Tamzek · 07-08-2003, 02:57 PM

Hey! When I was a kid I learned about brontosaurus. Then, later on, I learned that the name had been officially changed to apatosaurus, and I and other nerds took great pleasure in snottily correcting people.

So what's the current terminological situation? And why can't the damn taxonomists keep the names straight?

Veovis · 07-08-2003, 08:18 PM

Actually it is officially Apatosaurus, but I think some still call it Brontosaurus. Bob Bakker called it Brontosaurus in his book, The Dinosaur Heresies.

Also, If this Antetonitrus is only 2 meters high and 2 tons (metric?), than wouldn't it be considered a prosauropod? Which period of the Mesozoic did it live in?

ps418 · 07-09-2003, 12:06 PM

Nic and Veovis --you're both right, of course. Its Apatosaurus.

Personally, I blame the Flintstones for this persistent taxonomic confusion.

Patrick

MrDarwin · 07-09-2003, 12:13 PM

Quote:

Originally posted by Nic Tamzek
Hey! When I was a kid I learned about brontosaurus. Then, later on, I learned that the name had been officially changed to apatosaurus, and I and other nerds took great pleasure in snottily correcting people.

So what's the current terminological situation? And why can't the damn taxonomists keep the names straight?

I don't know the details, but my understanding is that Apatosaurus was published first and thus has nomenclatural priority, regardless of how widely the name Brontosaurus has been used. So the name wasn't changed so much as restored.

Skydancer · 07-10-2003, 09:58 AM

Quote:

Originally posted by MrDarwin
I don't know the details, but my understanding is that Apatosaurus was published first and thus has nomenclatural priority, regardless of how widely the name Brontosaurus has been used. So the name wasn't changed so much as restored.

Exactly. Complicated by the fact that due to the incompleteness of the fossils, they didn't realize it was the same animal until quite a bit later - so there's a lot of official literature under both names.

07-08-2003, 01:20 PM	#3
lpetrich Contributor Join Date: Jul 2000 Location: Lebanon, OR, USA Posts: 16,829	Four legs -> two legs -> four legs First, I mean by "leg" a limb used for walking. Especially interesting here is how sauropods had been descended from two-legged ancestors that had moved back to walking on all fours. This has clearly happened among other herbivorous dinosaurs, like Stegosaurus and the duckbills, where their outsized hind legs give away their two-legged ancestry. However, the carnivores had stayed two-legged, as have their surviving offshoot, the birds. The earliest dinosaurs, like Herrerasaurus, had been two-legged, but most legged reptiles have been four-legged, including the closest surviving relatives of the dinosaurs, the crocodilians. So the four-legged dinosaurs have done: four-legged -> two-legged -> four-legged (early reptiles) (early dinosaurs) (some later dinosaurs) and have gone back to all fours more than once.

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07-08-2003, 12:34 PM	#2
Rhaedas Veteran Member Join Date: Mar 2003 Location: USA Posts: 3,440	I can't wait for the creationists' "yes, but where's the transitional fossils between those fossils and Brontosaurus?" :banghead:

07-08-2003, 02:57 PM	#4
Nic Tamzek Senior Member Join Date: Jan 2002 Location: California Posts: 646	Hey! When I was a kid I learned about brontosaurus. Then, later on, I learned that the name had been officially changed to apatosaurus, and I and other nerds took great pleasure in snottily correcting people. So what's the current terminological situation? And why can't the damn taxonomists keep the names straight?

07-08-2003, 08:18 PM	#5
Veovis Veteran Member Join Date: Jul 2003 Location: Portland-upon-Willamette Posts: 1,840	Actually it is officially Apatosaurus, but I think some still call it Brontosaurus. Bob Bakker called it Brontosaurus in his book, The Dinosaur Heresies. Also, If this Antetonitrus is only 2 meters high and 2 tons (metric?), than wouldn't it be considered a prosauropod? Which period of the Mesozoic did it live in?

07-09-2003, 12:06 PM	#6
ps418 Veteran Member Join Date: Mar 2001 Location: Louisville, KY, USA Posts: 1,840	Nic and Veovis --you're both right, of course. Its Apatosaurus. Personally, I blame the Flintstones for this persistent taxonomic confusion. Patrick

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