Birds and the feather did not evolve together

Illustration of Microraptor, which is thought to have had iridescent feathers.

“Which came first, the chicken or the egg?” Evolutionarily speaking, it’s a yawn of a conundrum. We know it was the egg, which evolved (with shell to enable a terrestrial lifestyle) some 300 million years ago, long before a chicken first clucked across a patch of open ground.

In between the origin of the egg and the domestication of the chicken, however, there are plenty of other interesting features to consider. Take the feather. There were hints of a revolution 150 years ago when part-dinosaur, part-bird archaeopteryx was discovered. Recently, discoveries in China have pulled back the curtain to reveal a varied cast of feathered dinosaurs, and we've found it wasn't just the direct ancestors of birds that were sporting down coats.

These discoveries have made the question of evolutionary origins even more interesting. At one point, you could have wondered whether feathers—which are basically made of the same stuff as scales— arose directly to aid flight or had been co-opted for the purpose from some other function. The prevalence of feathers and feather-like structures in flightless organisms points to the latter. So when did they first appear, and what were these other functions?

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NOVA series tours Earth history, Aussie style

Host Richard Smith with the modern stromatolites of Shark Bay.

Chris Taylor

It’s the geologist’s refrain: rocks tell stories. Geologists don’t (usually) get excited about a chunk of sandstone just because it’s sandy. It’s the secrets it holds—secrets about a world in the past that we can never visit, even as we stand on its consequences.

“Australia’s First 4 Billion Years," a four-part series that begins April 10th on NOVA, recounts the tale of Earth’s history the right way—by letting the rocks tell it. And it does so without even leaving the land down under (save a short stop in New Zealand).

That’s not a limitation, it’s a strength. It allows the program to hone in on details that many won't have heard before, rather than providing a montage of interesting events around the world—an approach that usually yields only the most familiar ones. The program builds an appreciation for the landscape, too, by allowing you to more fully explore the rich history of a region. Besides, Australia’s geology lays bare an impressive amount of geologic time. You could do much worse as far as locations go.

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Dinosaur-killing impact set the world on fire

NASA

The mass extinction events that we understand well all seem to have relatively local causes: volcanic activity in Asia or Pangea, an impactor striking the Yucatan. But the events are so large that the environmental disruption goes global, killing off species across the planet and even in ecosystems, like the oceans, that might not be directly affected.

Massive volcanic eruptions can clearly create global destruction by dimming sunlight, causing sudden climate swings and acidifying the ocean. But it might be a bit harder to see how the impact of a large rock from space can reach into habitats halfway around the globe. Yet that's exactly what we think happened during the extinction that killed off all the non-avian dinosaurs (along with a host of other species). A paper in the Journal of Geophysical Research reviews the evidence for what its authors consider the most plausible model for global mayhem caused by the impact: its debris lit all the world's forests on fire at once.

The basic outlines of the scenario are pretty straightforward. The energy released by the impact sent lots of material high into and above the atmosphere, a lot of it near the escape velocity, which allowed it to spread around the planet. That is, after all, how we got the global layer of iridium that pointed to an impact being involved in the first place. But it's this material's return through the Earth's atmosphere that caused problems for vegetation. The heat of re-entry for all this material set off what's termed a "global infrared pulse."

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Extinction that paved way for dinosaurs definitively linked to volcanism

The formation of these innocent looking rocks killed off most of the species alive at the time, but worked out well for the dinosaurs.

NY DEC

Although we tend to think of the Earth as an amazingly hospitable planet, at several times in the past it seems to have done its best to kill us all—or at least all of our ancestors. Several of the Earth's mass extinctions occurred around the time of elevated volcanic activity, but the timing has been notoriously difficult to work out; the fossil beds that track the extinction rarely preserve the evidence of volcanic activity and vice-versa.

A study that will appear in today's issue of Science provides a new window into the end-Triassic mass extinction, the event that ushered in the start of the era of the dinosaurs. The study provides a precise timing of events of the extinction through a combination of new dating work and a link to the Earth's orbital cycles preserved in rocks near Newark, New Jersey (because when you think end-Triassic, you think New Jersey, right?). The timing of events shows that the extinction occurred at the very onset of the volcanic activity that signaled the breakup of the supercontinent Pangea, but that life began to recover even as the later eruptions were taking place.

Thinking big

Volcanic activity takes place all the time and, while it can be devastating for the local environment (and you can use a very large definition of "local" for supervolcanoes), this isn't enough to set off a global extinction. For that, you need what are termed "flood basalt eruptions." These events are just what the name implies: molten rock comes flooding out of a rift, and covers thousands of square kilometers in rock, often at depths of hundreds of meters. And then, before the Earth recovers, you do it all over again. The largest of these eruptions, which formed the Siberian Traps, has had the total volume of rock that erupted estimated at above a million cubic kilometers.

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Study: early birds had four wings

Philippa Warr

The ancestors of modern birds probably had four wings rather than two, according to a study of fossils found in a Chinese museum.

The four-winged early birds had been identified from fossilised remains a number of years ago, but it was unclear whether the creatures were precursors to modern birds or whether they represented an evolutionary cul-de-sac and had simply died out.

However, eleven skeletons of primitive birds discovered at the Shandong Tianyu Museum of Nature feature evidence of having large feathers on their hind limbs. The remains date from the early Cretaceous period (around 120 million years ago) and, according to the study, "provide solid evidence for the existence of enlarged leg feathers on a variety of basal birds".

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Cretaceous meteor arrived just in time to wipe out the dinosaurs

UC-Berkeley geologist Paul Renne at the study site in Montana.

Courtney Sprain

Of all the mass extinction events in Earth’s history, the most familiar is probably the one that wiped out the dinosaurs and ushered in the age of the mammals. Most of us know the story—a hellish meteor impact that dragged about 3 out of every 4 species into extinction.

But the story is more complicated than that. There was also a series of incredibly massive and long-lived volcanic eruptions—they formed the Deccan Traps—around the same time. A second smoking gun, if you will. So which one did in the dinosaurs? Well, that depends on when the bullets were fired.

The debate started with the discovery of a layer of clay present throughout the world, and situated right at the boundary of the Cretaceous and (more recent) Paleocene rocks, marking the point where the fossils suddenly change. In the clay, there was a curiously sharp spike in iridium—an element that is generally rare in Earth’s crust. That suggested an extraterrestrial visitor (of the rocky and violent kind), since some asteroids are rich in elements like iridium.

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Re-re-re-thinking the rise of mammals and death of the dinosaurs

Grandma? An artist's conception of the appearance of the first placental mammal.

Carl Buell

The end of the era of dinosaurs and rise of the mammals has held a fascination for me since I was young (and I suspect I'm not alone). But it's a tale that has been retold many times now.

In the earliest versions, I recall ideas about clever, fast-moving mammals outcompeting the slow, lumbering dinosaurs. With time, however, that story changed. The dinosaurs became quicker and actually survived, albeit as birds (papers now refer to the loss of "non-avian dinosaurs"). The mammals became less clever and more lucky, in that it took a freak hit from an asteroid to trigger the mass extinction. As DNA data came in, the amount of luck involved seemed more and more significant. Data indicated some of the lineages of modern placental mammals had been around for millions of years before the dinosaurs died, but didn't really do much until after the extinction event.

A new analysis, published in Science now pushes back against the molecular data. A large team of authors tracked thousands of individual traits in more than 125 species (40 of them known only from fossils) to build the biggest reconstruction of the history of mammals ever attempted. In doing so, they find the first placental mammal probably didn't exist until after the non-avian dinosaurs were gone, the study even provides some hints of what it might have looked like.

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Mystery donor who gave $35K to The Oatmeal’s Tesla museum fund revealed

A mock-up of a room in the forth-coming dino hotel.

Greg Tally, owner of the Best Western Denver Southwest hotel, was one of two mystery donors behind donations of over $33,333 that helped Matt Inman raise almost $1.4 million to buy property in Long Island for a Tesla Museum. But Tally, who says he donated $35,000, isn't just a hotelier. The self-professed “science lover and Colorado history buff” broke ground on Tuesday, initiating a construction project that will transform his regular hotel into a dinosaur and paleontology themed hotel.

In an e-mail to Ars, Tally said that besides the publicity he knew would receive from the donation (The Oatmeal promised to write a cartoon about donors that gave more than $33,333), he also just likes museums in general. “I'd like to see Wardenclyffe [the name of the property that will become the Tesla museum] joined [by] a 'Tesla West' museum in Colorado Springs. (I have no businesses there; just seems like a great attraction for the state). I'm gaga about museums. Plus, I want to educate the world about why Dinosaur Ridge, The Morrison Formation, The Cretaceous Interior Seaway and the Dakota Hogback are significant for culture, history and paleontology” (Links added by the editor).

Dinosaur Ridge is famous for some of the best-known and earliest fossil discoveries in the US, including “Apatosaurus, Stegosaurus, the Colorado State Fossil; and Allosaurus,” according to the visitor center website (Who knew states had official fossils? My state, California, bears the standard of the saber-toothed cat, and Georgia Representative Paul Broun, who declared, 'All that stuff I was taught about evolution and embryology and the Big Bang Theory...is lies straight from the pit of Hell,' defends the Cretaceous–Miocene shark tooth as his state fossil.) Dinosaur Ridge is a few minutes drive from the site of Tally's hotel, which will feature fossil displays and life-size dinosaur statues when complete.

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Xenoceratops: the ‘alien horned-face’ dinosaur discovered in Canada

A new species of horned dinosaur, called the xenoceratops—"alien horned-face"—has been discovered in fossil beds in Alberta, Canada.

The discovery is based on remains from at least three adult-sized individuals, which were identified from fossils originally collected in 1958. The creatures would have been approximately six meters long and would have weighed more than two metric tons each.

The xenoceratops was a herbivore with a parrot-like beak, two long brow horns above its eyes and a large frill protruding from the back of its skull with two additional large spikes. It lived around 80 million years ago, making it one of the oldest ceratopsids, the group of large-bodied horned dinosaurs that includes triceratops.

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Dinosaur bones reveal evidence against cold blooded creatures

Alpine red deer bone showing dark lines of arrested growth.

Meike Köhler

Who can get enough of dinosaurs? We’re curious about what color they were, how fast they moved, and whether they could really spit venom at Newman from Seinfeld. One of the most fundamental questions is whether they were cold-blooded or warm-blooded. Just because some of them looked like fearsome, giant lizards doesn’t mean they had to bask to raise their body temperature. After all, birds, likely their lone surviving descendants, are warm-blooded.

Researchers have looked at this question from many different angles (including temperature measurements from teeth, as we reported last year). One intriguing line of evidence has come from the microscale structure of their bones. Cross sections through fossils from most groups of dinosaurs (except sauropods) reveal cycles in growth, including dark lines where growth temporarily ceased.

This has long been cited as strong evidence in favor of cold-bloodedness, as the bones of modern cold-blooded species also show annual cycles. Since their body temperature is at the whim of the seasons, their growth slows during non-ideal conditions. Warm-blooded animals, on the other hand, keep their body temperature constant, and so their bone growth, too, remains constant. Or so the story went.

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