Deench

Everything for Everyone

Category Archives: paleontology

Recalibrated DNA clock suggests we can stop looking for early primate fossils

The earliest primate fossils unearthed thus far are only 56 million years old, but molecular estimates of the rate of primate evolution predict that there should be some dating back to the Late Cretaceous, closer to 82 million years ago. This is embarrassing for scientists, akin to the time in 1929 when Edwin Hubble measured the age of the Universe as less than half the age of the Earth. 

One possible explanation is that earlier fossils are out there, but that no one has found them yet. But Michael Steiper and Erik Seiffert have proposed an alternate reconciliation in a new study of the molecular rate of evolution. Their work was published in the Proceedings of the National Academy of Sciences.

Read the rest of this article...

Read the comments on this post


Feathers may have helped T. rex’s relatives ride out a cold climate

Feathers are the defining feature of birds, but that wasn't always the case. For millions of years, various species of dinosaurs sported feathers, some of which have left behind fossilized impressions. But for the most part, the feathers we've found have been attached to smaller dinosaurs, many of them along the lineage that gave rise to birds.

That situation was changed dramatically by a species that is described in today's issue of Nature. Three nearly complete skeletons have revealed a feathered dinosaur that its finders term "gigantic." At nearly 1,500kg and over forty times the weight of any previous feathered dinosaur, Yutyrannus huali was a beast—almost certainly an apex predator, and related to the ancestors of Tyrannosaurus Rex.

Read the rest of this article...

Read the comments on this post


The rock record got a bad rap. Fossil diversity accurately reflects history

Say an EKG machine is monitoring your heart, when it suddenly flatlines. You'd be keenly interested to know whether your heart had stopped or the machine had simply gone on the fritz. Paleontologists have faced a similar (if slightly less urgent) puzzle when it comes to the geologic record of life: does the fossil record we see reflect the state of ancient ecosystems, or is it just the readout from a defective instrument? A recent paper in Science gives reassuring support to the fidelity of the rock record.

It’s fascinating to study how species diversity has changed through time, since we can see the effects of major events in Earth’s past and watch evolution play out. It's literally reading the history of life on Earth. That’s a story we naturally want to know and tell. But fossils are difficult to come by—after all, less than one percent of extinct species are represented in the fossil record. As an imperfect recorder, we have to worry how much the evidence in the rocks is telling us about the organisms, and how much we're just seeing changes in the rocks themselves.

Read the rest of this article...

Read the comments on this post


It’s got 16,000 eyes on you—the vision of a Cambrian-era predator

Those of you who get a bit weirded out by spiders and other arthropods would probably have a coronary if an Anomalocaris were to swim in your direction. The animals were about a meter long, and shaped as a flattened oval, a bit like a modern flounder. That's about the only similarity with a fish, though. Instead of fins, the Anomalocarids propelled themselves through the water using a series of elongated paddle-like structures running down both edges of the body. In front, a pair of appendages could shovel prey into a circular mouth located on its underside.

And then there were the large, bulging eyes, springing from each side of the animal's head. Until now, we could only guess at what the eyes looked like, but some spectacular, 515 million-year-old fossils from Australia have now shown that they had a huge number of small lenses, arranged much like those in modern insects and other arthropods. The finding suggests that the compound eyes evolved right at the origin of this branch of the evolutionary tree, long before the sorts of hard exoskeletons we now consider typical of arthropods.

Read the rest of this article...

Read the comments on this post


Four-winged dinosaur fossilized after swallowing a bird

Feathered dinosaurs existed for millions of years before the origin of birds and, for a time, there was a period where feathered dinosaurs and early birds coexisted with animals that don't fit neatly into either category. One of the latter was microraptor, a feathered dinosaur that doesn't appear to have been of the avian lineage but still seems to have had wing-like feathers on all four of its limbs. Researchers have now found that microraptor did have a close relationship with birds: it ate them.

Microraptor, as its name implies, was a small dinosaur, maybe a meter long counting its tail. Based on the number of fossils we've recovered, it was about as unremarkable as a pigeon in its day, which was about 120 million years ago. But most reconstructions suggest it looked rather unusual by modern standards. That's because microraptor featured wing-like forelimbs that retained claws, and hindlimbs that had an array of feathers similar to that on its forelimbs. A number of researchers suggest it could fly or glide, possibly using all four limbs for lift.

Read the rest of this article...

Read the comments on this post