paleontology
razib | May 6, 2009There are two posts on ScienceBlogs which highlight two perspectives on the Dinosaur mass extinction, What Wiped Out The Dinosaurs? and K-T extinction debates: cranky "skeptics" or reasonable science?. I'd assumed that the Asteroids-from-the-sky was the clear consensus, but please see this old BloggingHeads.TV clip where Peter Ward seems to imply that the waters are muddier than you'd think:
gregladen | May 6, 2009Many years ago, a sudden event occurred that changed everything. Or at least, that is what we think now. But in truth, the event took longer than many today believe, and many of the specific details, the exact order of events, the actual meaning of each detail, are not fully understood. Indeed, in the process of describing this event today, we find considerable disagreement, or at least, it is clear that one person's version is different than another's. I'd be happy to give you my version of it. What qualifies me to do that? Well, for one thing, I was there when it happened...
I refer,…
laelaps | May 5, 2009
The Calaveras skull, front view. From Skeletal Remains Suggesting or Attributed to Early Man in North America.
In February of 1866 the Illinois-born blacksmith James Mattenson* decided to try his luck beneath Bald Hill in Calaveras County, California. There was a chance that the subterranean depths of the hill were streaked with gold, and to this end Mattenson sunk a mine shaft into the rock. For one hundred feet below the surface the hill was nothing but solidified lava, but fifty feet below that the hill was made up of interspersed layers of gravel and volcanic tuffs. Mattenson had…
gregladen | May 5, 2009Keller has been one of the leading voices opposing the impact KT boundary extinction hypothesis. According to a press release from her university, she has more on this matter.
Press Release:
Gerta Keller, whose studies of rock formations at many sites in the United States, Mexico and India have led her to conclude that volcanoes, not a vast meteorite, were the more likely culprits in the demise of the Earth's giant reptiles, is producing new data supporting her claim.
Keller, a Princeton professor of geosciences, and several co-authors lay out the case in a paper published April 27 in the…
laelaps | May 5, 2009Since Bora mentioned it...
The hungry hunters go after some jumbo-sized Syndyoceras.
laelaps | May 4, 2009
A swarm of hunters tries to take down a Uintatherium. Nevermind that it lived over 35 million years before the first hominins appeared...
laelaps | May 4, 2009By the 1920's the evolution of elephants (proboscideans) seemed all but resolved. Paleontologists had long been familiar with mammoths and mastodons, the great shaggy beasts that had so recently gone extinct, but in 1901 fitting candidates for the progenitors of all later elephants became known. Named Moeritherium and Palaeomastodon by British paleontologist C.W. Andrews, the two proboscideans from Eocene rock of the Fayum region of Egypt were the forms that could connect elephants to the rest of the mammal family tree.
Finally elephant evolution could be presented in a straight line. It had…
laelaps | April 30, 2009
The skull of Dorudon, photographed at the National Museum of Natural History.
There has been much ado about the new BioLogos website during the past week (see here and here), and most of it has focused on the site's aim of reconciling science and Christian theology. What irked me more, however, was the lazy way in which the creators of the site approached evolutionary science. The section on the fossil record provides a perfect example.
The evolution of whales has been a hot topic lately, and for good reason. After over a century of frustrating uncertainly we now have a very detailed (…
laelaps | April 30, 2009The news has already broken at SV-POW! and Tetrapod Zoology, but in case you haven't heard Mike Taylor has successfully defended his Ph.D.! This is wonderful news. I am sure that the study of sauropods will benefit from his continued work in the field.
My only regret is that I can't buy him a drink since I am not going to be able to make it to SVP in England this year. (I actually owe quite a few people a drink or two. At this rate I had better hope I win the lottery to cover the bar tab I will surely build up...) Earning a Ph.D. merits a few rounds alone, but Mike (among others) has provided…
razib | April 29, 2009New Geochronologic And Stratigraphic Evidence Confirms The Paleocene Age Of the Dinosaur-Bearing Ojo Alamo Sandstone And Animas Formation In The San Juan Basin, New Mexico and Colorado:
...An assemblage of 34 skeletal elements from a single hadrosaur, found in the Ojo Alamo Sandstone in the southern San Juan Basin, provided conclusive evidence that this assemblage could not have been reworked from underlying Cretaceous strata. In addition, geochemical studies of 15 vertebrate bones from the Paleocene Ojo Alamo Sandstone and 15 bone samples from the underlying Kirtland Formation of Late…
bioephemera | April 29, 2009
Check out Brian's new review of A History of Paleontology Illustration (Life of the Past) by Jane Davidson, in Palaeontologia Electronica:
It is rare for fossils to be featured in fine art, but in the 15th century painting A Goldsmith in His Shop, Possibly Saint Eligius by the Flemish master Petrus Christus there is, if you look carefully, a fossil shark tooth among the objects scattered on the shop's table. The fossil plays a nearly insignificant role in the painting, but it reflects the general interpretation of such natural curiosities at the time. From this modest starting point,…
laelaps | April 29, 2009
A view from inside the cave in which the "Yemisch" remains were found. [source]
It was not so long ago that tales of an awful creature that stalked the pampas of Patagonia were commonly told. It was difficult, if not impossible, to find anyone who had actually seen it, but many knew of its fearsome power. It was called the Yemisch, and it was a predator that preferred to disembowel its prey. One moment a person or some cattle would be crossing the stream and the next the water would be a blood-red boil. All that was usually left of the victims were greasy entrails floating their way…
laelaps | April 27, 2009
An illustration of the mammoth that accompanied Tukeman's story. From the McClure's Magazine.
In October of 1899 McClure's Magazine ran a rather curious article by Henry Tukeman. Called "The Killing of the Mammoth" it began with a letter penned by a recently-deceased chap named Horace Conradi which released Tukeman from his promise to keep the slaughter of what may have been the last living mammoth a secret. Tukeman could finally tell his story.
Tukeman's story began in the untamed wilds of Alaska in 1890. There was little in the way of creature comforts, but Tukeman decided to stay the…
laelaps | April 26, 2009After a long wait, the new Palaeontologia Electronica is now online! It even includes a review of Jane Davidson's A History of Paleontology Illustration by yours truly. Check it out!
laelaps | April 24, 2009About four million years ago, in the shallows of an ocean that once covered what is now southern Peru, a large shark bit into the jaw of a baleen whale. The whale had been dead for some time, but it was kept afloat but the gases building up in its body as it decomposed. It was absolutely rotten, but it still presented a free meal to the scavenging shark. As the shark bit down, however, one of its teeth became stuck in the whale's jaw bone and broke off. No matter. The lost tooth would soon be replaced by another.
The above scenario does involve a bit of speculation, but such events certainly…
laelaps | April 23, 2009True to his moniker, the Open Source Paleontologist (aka Andry Farke) often blogs about open access paleo journals. There are a lot out there, but which are the best ones to publish in? How do lesser-known publications like Geodiversitas rank among heavy hitters like PNAS or PLoS? Now you have a chance to have your say. Andy has created a survey asking you to rank the quality of the present span of open access journals that regularly publish paleontology papers. Voting will be open until Friday and the results will be revealed shortly afterward. Go vote!
laelaps | April 22, 2009Of all the evolutionary transitions that have ever taken place few have received as much attention as the origin of whales. (See here, here, here, here,and here for a few of my posts on the subject.) The story of how terrestrial hoofed mammals gave rise to the exclusively aquatic leviathans has been highlighted in headlines over and over again, but other marine mammals have not received the same amount of public attention. In the case of pinnipeds (seals, sea lions, and walruses) this may be at least partially due to the fact that their origins have been difficult to tease out.
It has long…
laelaps | April 20, 2009
A giraffe, photographed at the Bronx zoo.
Why do giraffes have long necks? We know that modern giraffes must have evolved gradually, but figuring out what selection pressures influenced giraffe evolution is another story altogether. One of the most popular recent explanations is that giraffes have long necks as a result of sexual selection.
The "necks for sex" hypothesis is primarily inspired by the contests between male giraffes. In these duels the males stand side by side and whack each other with their necks and ossicones ("horns"). This can be seen in the video below;
What does this…
laelaps | April 15, 2009
A somewhat thrown-together illustration about camel evolution. The series should be read C-D-E-F for the evolution of the forelimb and G-H-I-J for the hind limb. Compare this to more famous diagrams of horse evolution, like this one. From A text-book of geology for universities.
For more than a century fossil horses have stood as some of the most iconic examples of evolutionary change. From about 1870 onward it seemed that the ancestry of modern horses was represented by a nearly complete fossil series, but this is not to say that we have always perfectly understood these remains. Even…