Oldest Bird Found in China?

29 05 2013

A very interesting article about the new bird/dinosaur relative Aurornis xui was published this week in the British journal Nature.  It can be found at the Nature News Web site, here:  http://www.nature.com/news/new-contender-for-first-bird-1.13088.

Apparently, A. xui is a strong contender for “earliest bird”.  The extremely complete specimen was unearthed by a farmer in China’s Liaoning Province and acquired by the Fossil and Geology Park in Yizhou, China, through a fossil dealer, where it remained unidentified until being discovered by paleontologist Pascal Godefroit in 2012.

The article states that Godefroit believes that A. xui is “the oldest known member of the Avialae,” the group that includes all animals more closely related to modern birds than to dinosaurs.  This makes it the oldest bird, even older than Archaeopteryx.  A phylogenetic comparison of the specimen with approximately 100 other birds and dinosaurs seems to confirm this.

Godefroit goes on to say, “But these sorts of hypotheses are very controversial. We’re at the origins of a group. The differences between birds and [non-avian] dinosaurs are very thin.”

The American journal Science, also has an article about the find, which can be viewed here:  http://news.sciencemag.org/sciencenow/2013/05/earliest-bird-claim-ruffles-feat.html.  This article provides some additional background information about the evolutionary history of birds and dinosaurs.  It also points out the key remaining issue with the find – it’s authenticity.  There have been several famous fossil fakes from China in the last few years, most of which came to light through fossil dealers, as did A. xui, and one commentator in the Science article noted that scientists need to “take a skeptical look at this specimen.”  He stated that the fact that it is so complete and so “so neatly arranged” raises suspicions that needed to be put to rest before the specimen is completely accepted.

 

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Tyrannosaur a Whole Genus of Critters

28 03 2010
 
 
 
 
This image is courtesy of Wikimedia Commons.  It is by stu_spivack, and is licensed under the Creative Commons Attribution-Share Alike 2.0 Generic license.

At 12 feet long, this juvenile T. rex, known as Jane, which is on exhibit at Burpee Museum of Natural History in Rockford, IL, USA, is just slightly larger than the new Tyrannosaur recently discovered in Australia.

Tyrannosaurs are more than just the single species Tyrannosaurus rex, though that’s the one most people think about.  Tyrannosaurus is a genus, the next taxonomic order above a species, and consists of more than 30 species of dinosaur.  These species fall into the group of dinosaurs known as theropods, and lived during the late Jurassic and throughout the Cretaceous periods.  Tyrannosaurus rex is the most famous member of the genus, and the biggest physically.  It is also one of the latest, living during the last three- to four-million years of the Cretaceous, right up to the end of the age of dinosaurs.

 The number of Tyrannosaur fossils discovered to date has been so great (e.g., more than 30 skeletons of T. Rex, alone), that it has allowed scientists to study them as much or more than any other type of dinosaur.

Tyrannosaurs were bipedal carnivores, having long, heavy tails, relatively tiny (though very strong) front arms, and massive skulls.  While other theropod dinosaurs equaled or exceeded T. rex in size, it was the largest known tyrannosaurid and one of the largest known land predators of its day, measuring up to 12.8 meters (42 ft.) in length, 4 meters (13 ft.) tall at the hips, and weighing as much as 6.8 metric tons.

While definitely a carnivore, scientists have long debated whether T. rex was an apex predator or a scavenger.  The debate is one of the longest running arguments in all of paleontology.

The genus was widespread through the northern hemisphere, but until very recently was unknown from the southern one.  In March, 2010, scientists from Monash University in Melbourne, Australia, reported the discovery of a tyrannosaurid hip bone from Dinosaur Cove in southern Victoria, Australia.  This appears to be a smaller animal than T. rex, and likely a new species.

Researchers estimate that the animal was approximately three meters long and weighed about 80 kg.  As such, it would have been similar to, though slightly larger than a human.  It lived about 110 million years ago.

The following are a few of the Tyrannosaurus species that have been identified, who described them, and when they were described:

  • Tyrannosaurus amplus (Marsh, 1892)
  • Tyrannosaurus bataar (Maleev, 1955)
  • Tyrannosaurus lanpingensis (Yeh, 1975)
  • Tyrannosaurus luanchuanensis (Dong, 1979)
  • Tyrannosaurus rex (Osborn, 1905)
  • Tyrannosaurus turpanensis (Zhai, Zheng, and Tong, 1978)