Two new Homo fossils are described in this week’s Nature, and here they are.
Pharyngula
Evolution, development, and random biological ejaculations from a godless liberal
Two new Homo fossils are described in this week’s Nature, and here they are.
John Hawks reports that a certain well-known 3.2 million year old lady has quietly left her home in Africa, and is on her way to Texas. She’s probably also going to visit Chicago in 2009 — I’ll be sure to stop by and pay my respects then.
…you’ll like this paleontological flickrset.
The state department has approved a visit from an eminent foreigner: a certain 3.2 million year old australopithicene is going to be at the Houston Museum of Natural Science from 31 August 2007 through 20 April 2008…and then she’s going on tour. Future locations haven’t been determined yet, but Minneapolis is nice. Chicago would be OK. I hope I get a chance to pay court on her.
Just a thought, but the creationists have got it all wrong. They think we worship Charles Darwin, but actually, if there are any objects of reverence among evolutionary biologists, it would be the evidence — the bones of Lucy, of Archaeopteryx, of Tiktaalik, the little trilobite in shale that I keep by my hand at my office desk.
This is Gigantoraptor erlianensis, a newly described oviraptorosaur from late Cretaceous of China. It’s a kind of nightmare version of Big Bird — it’s estimated to have weighed about 1400kg (1½ tons for non-metric Americans).
Histological examination of the growth structure of the bones suggests that this fellow was a young adult, about 11 years old, and that they grew rapidly and reached nearly this size by the time they were 7. And since it is a young adult, there were probably bigger gigantoraptors running around. They also compared limb length to other dinosaurs, like the tyrannosaurs—gigantoraptor had longer, slimmer legs and was more of a runner than they were.
There’s no sign whether it was covered with bright yellow feathers.
Xu X, Tan Q, Wang J, Zhao X, Tan L (2007) A gigantic bird-like dinosaur from the Late Cretaceous of China. Nature advance online publication, 13 June 2007.
Science magazine has an article today on extracting and sequencing proteins from T. rex bones, and I’m already getting email from people wondering whether this is believable, whether it challenges the stated age of dinosaurs, whether this means we can soon reconstruct dinosaurs from preserved genetic information, and even a few creationists claiming this is proof of a young earth. Short answers: it looks like meticulous and entirely credible work to me, these fossil bones are really 68 million years old, and it represents a special case with limits to how far it can be expanded, so scratch “reassemble dinosaur from fragments” off your to-do list.
The latest Nature reveals a new primitive mammal fossil collected in the Mesozoic strata of the Yan mountains of China. It’s small and unprepossessing, but it has at least two noteworthy novelties, and first among them is that it represents another step in the transition from the reptilian to the mammalian jaw and ear.
Halkieriids are Cambrian animals that looked like slugs in scale mail; often when they died their scales, called sclerites, dissociated and scattered, and their sclerites represent a significant component of the small shelly fauna of the early Cambrian. They typically had their front and back ends capped with shells that resembled those we see in bivalve brachiopods. Wiwaxiids were also sluglike, but sported very prominent, long sclerites, and lacked the anterior and posterior shells; their exact position in the evolutionary tree has bounced about quite a bit, but some argument has made that they belong in the annelid ancestry, and that their sclerites are homologous to the bristly setae of worms. One simplistic picture of their relationship to modern forms was that the halkieriids expanded their shells and shed their scales to become molluscs, while the wiwaxiids minimized their armor to emphasize flexibility and became more wormlike. (Note that that is a very crude summary; relationships of these Cambrian groups to modern clades are extremely contentious. There’s a more accurate description of the relationships below.)
Now a new fossil has been found, Orthozanclus reburrus that unites the two into a larger clade, the halwaxiids. Like the halkieriids, it has an anterior shell (but not a posterior one), and like the wiwaxiids, it has long spiky sclerites. In some ways, this simplifies the relationships; it unites some problematic organisms into a single branch on the tree. The question now becomes where that branch is located—whether the halwaxiids belong in a separate phylum that split off from the lophophorate family tree after the molluscs, or whether the halwaxiids are a sister group to the molluscs.
Zimmer describes some of the more recent work on Flores Man — people are still arguing over whether the fossil is of a peculiarly abnormal human with microcephaly, or whether there was a species of ‘miniaturized’ Homo living on the islands of the Pacific. Trying to establish common characteristics of microcephalics is an interesting project, but it doesn’t answer the question. We need more fossils! Among the good news Carl mentions is the report that more excavations will be underway this year.
I reported a while back that there was a possibility that the phosphatized pre-Cambrian Doushantuo specimens might not be embryos—they might be a particular class of bacteria—but there may be evidence against that hypothesis. John Lynch finds a description of more advanced embryos, intermediate stages that would link at least some of the blastulae described so far to unambiguous multicellular organisms.
