Evolution Diary

Neil Shubin and his artist, Kalliopi Monoyios, have made available sets of Powerpoint slides from Your Inner Fish.

“In Your Inner Fish, Neil Shubin tells the story of evolution by tracing the organs of the human body back millions of years, long before the first creatures walked the earth. By examining fossils and DNA, Shubin shows us that our hands actually resemble fish fins, our head is organized like that of a long-extinct jawless fish, and major parts of our genome look and function like those of worms and bacteria. We have compiled the figures from the book into a deck of PowerPoint slides for use in the classroom.”

Go over to University of Chicago Website to download the slides.

The discovery of a dog-size T. rex ancestor may rewrite dinosaur evolutionary history, a new study says.

Measuring about 6 feet (180 centimeters) long–tail included–the 215-million-year-old Tawa hallae was found by hikers who noticed some small bits of bone at New Mexico’s fossil-rich Ghost Ranch.

The dinosaur bears a mix of characteristics, such as air sacs, that link Tawa to older dinosaur species found in South America, researchers say. Keep reading →

A new species of extinct pygmy sea cow (illustrated above with skull inset) is one of the first fossil mammal species found in Madagascar from the mysterious time period between 80 million years ago and 90,000 years ago, experts say.

“There’s a big gap where we really don’t know anything about what’s going on in the fossil record,” said study leader Karen Samonds, of McGill University in Montreal, Canada.

Sea cows, or sirenians, today include manatees and dugongs.

Known from a roughly 40-million-year-old skull and a few ribs, the new species has been named Eotheroides lambondrano, after the Malagasy word for dugong, which translates to “water bushpig.” At about seven feet (two meters) long, the ancient pygmy sea cow was smaller than the modern dugong, which ranges from about 8 to 10 feet (2.4 to 3 meters) in length.

The pygmy sea cow would have been “a neat in-between” animal in the evolution from primitive land-dwelling mammals to today’s aquatic sea cows, Samonds said.

E. lambondrano is also unique in that its closest relatives would have lived in what is now India and Egypt, according to the study—making its Madagascan location all the more special.

“This fossil gives us a new glimpse not just at a new time period, but at a new place,” said Samonds, whose work was funded in part by the National Geographic Society’s Committee for Research and Exploration.

“Madagascar already has a lot of strange beasts, and we now have a glimpse of this species from so far away.”

News from National Geographic

Findings published December 12 in the Journal of Vertebrate Paleontology.

Swarms of up to a thousand giant trilobites—extinct marine arthropods such as this 35-inch-long (90-centimeter-long) fossil specimen—roamed shallow prehistoric seas, new fossils show.

The 465-million-year-old fossils, found recently in northern Portugal, are of the largest trilobites ever discovered.

The trilobites may have clustered to mate and molt—shedding old exoskeletons as new ones grew in—as well as avoid predators, scientists say. Keep reading →

Jurassic Park was packed with pseudo-science, but one of its fictions may have accidentally anticipated a dinosaur discovery announced today—venomous raptors.

Though a far cry from the movie’s venom-spitting Dilophosaurus, the 125-million-year-old Sinornithosaurus may have attacked like today’s rear-fanged snakes, a new study suggests.

Rear-fanged snakes don’t inject venom. Instead, the toxin flows down a telltale groove in a fang’s surface and into the bite wound, inducing a state of shock.

In Sinornithosaurus fossils, researchers discovered an intriguing pocket, possibly for a venom gland, connected to the base of a fang by a long groove, which likely housed a venom duct, the study says. Sinornithosaurus fangs also feature snakelike grooves in their surfaces.

The Sinornithosaurus upper jaw has what may have been a pocket for a venom gland, a venom duct, and grooved teeth to aid venom delivery.

Illustration courtesy of National Academy of Sciences

Keep reading →