Limestone quarried in Italy and cut into slabs intended to be used for kitchen counters was found to have accidentally produced a perfect cross section of a 40 million year old Eocene fossilized whale.

National Geographic 6:31 video

Hat tip to Karen L. Myers.

Science News:

Results show modern humans, Neandertals diverged 660,000 years ago

An international consortium of researchers reports in the Aug. 8 Cell that for the first time the complete sequence of mitochondrial DNA from a Neandertal has been deciphered. Comparison of the Neandertal sequence with mitochondrial sequences from modern humans confirms that the two groups belong to different branches of humankind’s family tree, diverging 660,000 years ago.

That date is not statistically different from previous estimates of the split between humans and Neandertals, says Erik Trinkaus, a paleoanthropologist at Washington University in St. Louis. The sequence also doesn’t reveal what happened to drive Neandertals to extinction, but it does clear up some discrepancies in earlier studies. …

At 16,565 bases long, the new sequence is the largest stretch of Neandertal DNA ever examined. The DNA was isolated from a 38,000-year-old bone found in a cave in Croatia.

“It’s a nice accomplishment and the next important step toward completing the Neandertal genome,” says Stephan Schuster of Pennsylvania State University in University Park. Schuster is part of a group that is sequencing the genomes of the mammoth and other extinct animals, but was not involved in the current study. “It’s a nice landmark on the way to saying what makes modern humans so special.”

In order to know exactly how modern humans and Neandertals differ, scientists will need to examine DNA from the Neandertal’s entire genome. The sequence reported in the new study was generated as part of a project to decode Neandertal DNA, but it contains information only about DNA from mitochondria.

Mitochondria are organelles that generate energy for a cell. Inside each mitochondrion is a circular piece of DNA that contains genes encoding some of the key proteins responsible for power generation. Mitochondria are passed down from mothers to their children. Scientists use variations in mitochondrial DNA as a molecular clock to tell how fast species are evolving.

Scientists have previously examined a short piece of Neandertal mitochondrial DNA known as the hypervariable region, but this new complete sequence helps clear up some ambiguities from studies comparing Neandertals and humans, says John Hawks, a biological anthropologist from the University of Wisconsin–Madison.

Some modern humans have several changes in the hypervariable region that made it seem as if Neandertals are more closely related to modern humans than humans are to each other.

“Comparing the complete mitochondrial DNA genomes of a Neandertal and many recent humans presents a very different picture,” Hawks says. “Humans are all more similar to each other, than any human is to a Neandertal. And in fact the Neandertal sequence is three or more times as different, on average, from us as we are from each other. This change from the earlier picture is a purely statistical one, but it makes a clearer picture.”

Human and Neandertal mitochondrial DNAs differ at 206 positions out of the 16,565 examined, while modern humans differ at only about 100 positions when compared with each other.

UK News:

A period of prehistoric global warming and not the decline of the dinosaurs could be responsible for the rise of mammals, it was claimed today.

Scientists have drawn up a new “tree of life” tracing the history of all 4,500 mammals on Earth which shows they did not spread as a result of the massive asteroid strike that killed off the dinosaurs 65 million years ago.

Most palaeontologists believe the extinction of T Rex and his terrifying cousins permitted our ancestors to flourish and begin the long evolutionary process culminating in the diverse array of species we see today.

But an international team of researchers, which has taken more than a decade to chart modern mammals from existing fossil records and new molecular analyses, show many of the genetic ‘ancestors’ of the mammals existed 85 million years ago – and survived the meteor impact that is thought to have wiped out the dinosaurs.

However, throughout the Cretaceous period 144 to 65 million years ago, when dinosaurs walked the earth, these mammal species were relatively few in number and were prevented from diversifying and evolving in ecosystems dominated by dinosaurs.

The tree of life published in Nature shows after the asteroid strike certain mammals did experience a rapid period of diversification and evolution.

But most of these groups have since either died out completely such as Andrewsarchus – an aggressive wolf-like cow – or declined in diversity such as the group containing sloths and armadillos.

The researchers believe our ‘ancestors’, and those of all other mammals on earth now, began to radiate around the time of a sudden increase in the temperature of the planet – ten million years after the death of the dinosaurs.

Biologist Professor Andy Purvis, of Imperial College London, said: “Our research has shown for the first 10 or 15 million years after the dinosaurs were wiped out present day mammals kept a very low profile while these other types of mammals were running the show.

“It looks like a later bout of ‘global warming’ may have kick-started today’s diversity – not the death of the dinosaurs.

“This discovery rewrites our understanding of how we came to evolve on this planet – and the study as a whole gives a much clearer picture than ever before as to our place in nature.”

Abstract of Nature article.

Hat tip to José Guardia

Paleontologists excavating in the Riversleigh Fossil Beds (also) in Northern Australia have made some exciting finds:

Palaeontologists digging in northern Australia claim to have found the fossilised remains of the ultimate fighting marsupial – a flesh eating “killer kangaroo” that had wolf-like fangs and once walked the earth more than 10 million years ago.

The team from the University of New South Wales made the discovery along with 20 other previously unknown species in northern Queensland, including the carnivorous kangaroo, known as Ekaltadeta, and a large predatory bird described by the team as a “demon duck of doom”.

The vertebrate palaeontologist Sue Hand said the meat-eaters would have looked remarkably different from kangaroos around today. “These things had slicing crests that could have crunched through bone and sliced off flesh,” she said.

Professor Michael Archer, another team member, described the remains of two kangaroo species, one with wolf-like fangs and another with long forearms that was unable to hop like a modern kangaroo. “Because they didn’t hop, these were galloping kangaroos, with big, powerful forelimbs. Some of them had long canines like wolves,” he said.

The killer marsupial and duck of doom flourished in the Miocene epoch.

The discovery of a new fossil in China, Castorocauda lutrasimilis, demonstrates that mammals appeared early, and in larger forms, than previously believed, living at the same time as dinosaurs.

The San Francisco Chronicle story reports:

The remarkable fossil bones of a fur-covered, swimming mammal that lived in the age of the dinosaurs 164 million years ago have been discovered in China, raising a wave of excitement among scientists whose timetable for mammalian evolution has just been pushed back by 100 million years.

The animal appears to have been more than a foot long and weighed nearly 2 pounds, with a tail remarkably like a beaver and seal-like teeth clearly adapted for catching and eating fish, its discoverers say…

..The furry mammal was found in a rich fossil bed in Inner Mongolia’s Ningcheng county, about 160 miles northeast of Beijing. Its nearly complete skeleton was extracted from a rock layer along with the bones of small, two-legged meat-eating dinosaurs, primitive winged reptiles and the abundant remains of long-extinct crustaceans.

The rocks encasing the fossil skeleton bore the clear imprint of the dense hairs that had covered its body when it died in the mud and the horny scales that covered its flattened tail, the scientists said. They named their animal Castorocauda lutrasimilis and said it must have resembled a modern river otter or the “duck-billed” platypus of Australia.

William Clemens, professor emeritus at UC Berkeley and a former director of the Museum of Paleontology there, said the discovery provides “really good evidence” that the animal was both a swimmer and a fish-eater.