CAROTENOID PIGMENTS MAKE EXTINCT DUCK A RARE BIRD INDEED

The pink-headed duck was no lucky duck. In 1948 a single specimen of this waterfowl,Rhodonessa caryophyllacea, was donated to the Division of Birds of the Smithsonian’s National Museum of Natural History. The following year was the last time anyone spotted one of its species—which lived in Bangladesh, Nepal, India and Myanmar—alive.

Now, despite that it is likely extinct, new research has revealed this bird was a rare duck indeed. By shining lasers on the pink head feathers of the lone Smithsonian specimen and analyzing the spectral wavelengths of reflected light, Daniel Thomas of Massey University, New Zealand, and Smithsonian ornithologist Helen James determined it is one of only two species of waterfowl known to incorporate carotenoid pigments in its plumage. Carotenoids are of special interest to scientists because the evolutionary history of their appearance in bird plumage is unresolved. A paper on their study was published recently in the journal The Auk: Ornithological Advances, with Thomas as principle author.

Carotenoid pigments originate in what a bird eats and many of the most vibrant feather colors (red, orange, yellow) are the result of carotenoids, James explains. “Some come straight into the plumage from the diet unmodified and some are modified physiologically by the bird before they go into the plumage.” Flamingoes, for example, get their pink color from the carotenoid pigments in the brine shrimp and blue-green algae they eat.

“There are about 40 types of molecules classed as carotenoid pigments that have been found in bird plumage, they are very common in the songbirds, but until recently it had been thought there were none in waterfowl—ducks, swans and geese,” James adds. “Most visible colors in waterfowl plumage are a combination of melanin pigments, which are not ingested, and structural colors, which are not a pigment but just the structure of the feather.”

In 2014 James and Thomas discovered carotenoid pigments, for the first time, in the plumage of a duck: Australia’s pink-eared duck (Malacorhynchus membranaceus). This bird has tiny pink ‘ear’ spots on each side of its head. “So, we were curious about the pink-headed duck,” James says.

The two scientists then used Raman spectroscopy to study the pigments in the pink-headed duck’s feathers because it is a process that would not damage the Smithsonian’s lone specimen. Traditional methods for identifying pigments in feathers require plucking some feathers and destroying them. During the study Raman spectra were collected from the feathers of 20 other bird species in the Natural History Museum collections to provide a comparative dataset for studying the carotenoids found in the pink-eared and pink-headed duck. Raman analysis of both pink-headed and pink-eared duck plumage suggests that the pink plumage of both birds may be colored with the same type of carotenoid pigment.

“Yet these two ducks are not close evolutionary relatives within the family tree of ducks, waterfowl and geese,” James points out. An inflated balloon-shaped bony structure or bulla in the trachea of male pink-headed ducks has fenestrae or little windows in it—a type that is only found sea ducks and diving ducks, James says. The pink-eared duck is more closely related to stiff tailed ducks. “So it appears the deposition of carotenoids into their plumage was a step that arose separately in each species.”

This coincidence has James pondering a deeper evolutionary question, she says. “Is there a metabolic pathway for putting a carotenoid from the bloodstream into a developing feather that was just turned on or turned off and it happened to be only turned on in these two species of modern Anseriformes [ducks, geese and swans]? This is not a question we can answer. It is one that interests us though.”

Just what the pink-headed duck had in its diet that contained the carotenoid pigments that made its head pink is also a question no one can answer. “Almost nothing is known about what they ate. We really have so little information.” As the duck now appears to be extinct this question may never be known. smithsonianscience.si.edu

echinoid spine terminology

thefossilforum.com

tuba city, az dinosaur tracks

South African Cave Yields Strange Bones Of Early Human-Like Species

Scientists have discovered the fossilized remains of an unusual human-like creature that lived long ago. Exactly how long ago is still a mystery — and that's not the only mystery surrounding this newfound species.

The bones have a strange mix of primitive and modern features, and were found in an even stranger place — an almost inaccessible chamber deep inside a South African cave called Rising Star.

"It is perhaps one of the best known caves in all of South Africa," says Lee Berger, who studies human evolution at the University of the Witwatersrand, Johannesburg.

In 2013, some local cavers found some fossils inside Rising Star cave. Berger had asked them to be on the lookout, so they brought him photos.

"And there I saw something I perhaps thought I'd never see in my life," recalls Berger. "That is, clearly primitive hominin remains lying on the floor of a cave."

A jaw and a skull were just sitting there in the dirt — usually such bones are encased in rock.

Berger was excited, but he knew he personally could never reach this fossil site. To get into the cave chamber, you have to climb a steep, jagged rockfall called Dragon's Back, then wiggle through a small opening that leads to a long, narrow crack.

The crack is only about 7 ½ inches wide, and goes down more than 30 feet. Squeezing through it is the only way to reach the chamber of bones at the bottom.

Since he couldn't go, Berger sent in his tall, skinny 16-year-old son. "When he came out after 45 minutes, he stuck his head out. And to tell you how bad I am, I didn't say: 'Are you OK?' I said: 'And?' And he says, 'Daddy, it's wonderful.' "

Berger got funding from the National Geographic Society to excavate the site. And he advertised for research assistants on Facebook — for skinny scientists who weren't claustrophobic. Six women took the job.

They worked in the chamber almost like spacewalkers, communicating with researchers outside, via cameras and about 2 miles of fiber optic cable. The team in the chamber used paintbrushes and toothpicks to gently unearth fossil bones — there were more than 1,550 of them, an incredible treasure trove. The researchers describe their find Thursday in a journal called eLife.

"Often I was wondering, 'How on Earth are we going to get that fossil out?' because the density of bones in that chamber was so great, it was like a puzzle to get each fossil out," says Becca Peixotto, one of the scientist-cavers and a doctoral student in anthropology at American University.

The bones come from at least 15 individuals, says John Hawks, a paleoanthropologist from the University of Wisconsin-Madison, who was on the team that studied the bones.

"We have every age group represented" among the fossils, he says. "We have newborns; we have children of almost every age; we have adults and old adults."

He says these creatures were short — less than 5 feet tall — and thin. They have a particular combination of features that has never been seen before. "It's a new species to science," says Hawks. Researchers have named it Homo naledi, because "naledi" means "star" in a local South African language.

"They have a very small brain. They are not human-like at all in their brain," Hawks says. "It's around a third the size of a human brain today."

But the creatures had feet like us, and walked in a very human-like way. Their hands were also like ours, but their fingers were more curved.

The researchers also tackled this question: How did these human-like creatures get into such a crazy spot? It looks as though the cave chamber has always been hard to reach.

There are no animal bones there, except for a handful of bits from birds and mice. There's no evidence that a carnivore dragged the human-like creatures in, or that they somehow got washed in. And there's no evidence of a mass death, such as a cave accident.
Berger believes someone had to have put the bodies there.

"Homo naledi was deliberately disposing of its dead in a repeated, ritualized fashion in this deep underground chamber," he says.

That's quite a claim — that kind of ritual has been thought to be unique to modern humans or our very close relatives.

And really, the whole discovery — from the bones to their bizarre location — has perplexed experts on human evolution.

"To be honest, I would really distrust anyone who thinks they understand what the significance of these finds is," says Bernard Wood, a paleoanthropologist at George Washington University.

Usually scientists can tell how old fossilized bones are, but in this case the geology of the cave gives no clues. The bones could be less than 100,000 years old or several million years old.

"These folks do not have an age, yet they have some remarkable fossils, and the context of them is also remarkable," says Wood. "It's not only remarkable, it's also rather weird. But nonetheless, the fossils are important. So the community is, I think, struggling to work out what it all means."

He notes that only a small section of the cave chamber has been excavated, and it looks like many more bones are down there.

"There is the potential for thousands of specimens in that cave," says Wood. "Intellectually, it's a real puzzle. And I think it's going to take scientists quite a time to get their heads around what the real significance of these discoveries is." npr

Fossil Specimen Reveals a New Species of Ancient River Dolphin

Smithsonian scientists and colleagues have discovered a new genus and species of river dolphin that has long been extinct. They made the discovery after carefully examining fossil fragments from Panama. The fossil fragments also shed new light on the evolution of today’s freshwater river dolphin species. The team’s research was published Sept. 1 in the scientific journal Peer J.

The fossil, which dates from 5.8–6.1 million years ago, was found on the Caribbean coast near the town of Piña, Panama. It consists of half a skull, lower jaw with an almost entire set of conical teeth, right shoulder blade and two small bones from the dolphin’s flipper. In comparison with other river dolphins—both fossil and living—the shape and size of these parts suggests that the full specimen may have been more than 9 feet long.

Today there are only four species of river dolphins―all living in freshwater or coastal ecosystems and all endangered, including the Yangtze river dolphin, which is likely now extinct. Each of the modern river dolphin species show a common solution to the problem of adapting away from marine to freshwater habitats by converging upon a body plan that includes broad, paddle-like flippers, flexible necks and heads with particularly long, narrow snouts—all the better to navigate and hunt in winding, silty rivers.

But fossil evidence suggests that river dolphins’ ancestors were widespread around the globe. I. panamensis was clearly one of them, and its fossil remains have helped the team understand something less clear: When in their evolutionary tract did river dolphins transition from the saltwater of the ocean to the freshwater of rivers?

“We discovered this new fossil in marine rocks, and many of the features of its skull and jaws point to it having been a marine inhabitant, like modern oceanic dolphins,” said the study’s lead author Nicholas D. Pyenson, curator of fossil marine mammals at the Smithsonian’s National Museum of Natural History. “Many other iconic freshwater species in the Amazon, such as manatees, turtles and stingrays have marine ancestors, but until now, the fossil record of river dolphins in this basin has not revealed much about their marine ancestry. Isthminia now gives us a clear boundary in geologic time for understanding when this lineage invaded Amazonia.”

Other fossilized animals found at the same site as I. panamensis were marine species, indicating that unlike river dolphins living today, I. panamensis lived in the salty waters of a food-rich Caribbean Sea, before the full closure of the Panama Isthmus.

“Isthminia is actually the closest relative of the living Amazon river dolphin,” said study co-author Aaron O’Dea, staff scientist at the Smithsonian Tropical Research Institute in Panama. “While whales and dolphins long ago evolved from terrestrial ancestors to fully marine mammals, river dolphins represent a reverse movement by returning inland to freshwater ecosystems. As such, fossil specimens may tell stories not just of the evolution these aquatic animals, but also of the changing geographies and ecosystems of the past.”

The Smithsonian’s Digitization Program Office collaborated with the scientific team to create a high-resolution 3-D scan of the fossil, allowing the scientists to create 3-D prints of the delicate specimen, whose bones are too fragile to be molded and casted by traditional approaches. A 3-D print of the fossil is on permanent display at Panama’s BioMuseo—the original specimen will remain in the Smithsonian’s collection at the National Museum of Natural History. The public can also explore and download high resolution scans of the dolphin’s skull, jaw and shoulder blade at the Smithsonian X 3-D website 3D.SI.EDU.

The fossil was discovered by Dioselina Vigil, then a STRI intern and student at the University of Panama. The name of the new genus, Isthminia, recognizes both the Panama Isthmus and the fossil specimen’s living relative, the Amazon river dolphin, Inia geoffrensis. The study’s authors chose the species name, panamensis, to recognize the Republic of Panama, its people, and the many generations of scientists who have studied its geological and biological histories. smithsonianscience.si.edu

Scientists Discover One Of The Oldest Horned Dinosaurs: Wendiceratops

Scientists have found a "new" horned dinosaur that lived about 79 million years ago — and they say the discovery helps them understand the early evolution of the family that includes Triceratops.

The new dinosaur, which was named Wendiceratops pinhornensis after a famous fossil hunter who discovered the bone bed in Canada where these fossils were buried, is one of the oldest known horned dinosaurs.

Its distinctive feature is a highly decorated frill around its neck, says paleontologist David Evans from the Royal Ontario Museum.

"The frill is sort of ornamented by a pretty spectacular wave of gnarly hooks that project forward," Evans says.

He adds that it probably had big horns above its eyes and had a big one over its nose — the earliest occurrence of a prominent nose horn in this dinosaur family.

"It's a significant discovery in that it tells us a lot of new information about the early evolution of skull ornamentation, the hooks and horns, that characterize this iconic group of dinosaurs," Evans says.

A few decades ago, scientists knew of only 25 to 30 horned dinosaurs. Now, there are more than 60 and new ones keep turning up all the time.

Michael Ryan, a paleontologist with the Cleveland Museum of Natural History, says that Triceratops may have used its horns to fend off Tyrannosaurus rex in the late Cretaceous. But all these weird skull decorations in other dinosaurs likely had more to do with impressing the ladies.

"The horned dinosaur with the biggest horns may have been able to out-compete its rivals to control the biggest harem for breeding purposes," Ryan says.

He and Evans describe their new dinosaur in the journal PLOS ONE.

Despite this — and all the other new discoveries — Triceratops will likely continue to reign as the quintessential horned dinosaur, even though it is "actually a relatively boring horned dinosaur in many ways," Evans says.

But it was discovered over a century ago and has had time to get firmly lodged in the public's imagination. What's more, the fact that it lived in the time of T. rex means that children can play out epic battles between them.

"When I was a kid, Triceratops certainly loomed large in our household," says Evans, who recalls that it was his sister's favorite, while he preferred T. rex. "So, we kind of had the classic argument about which one was better when I was maybe 5 years old."

And he isn't the only one with such vivid Triceratops memories. Ryan recalls that his kindergarten teacher once read a children's book called The Enormous Egg.

"Because it was all about Triceratops and horned dinosaurs," Ryan says, "that probably set me on my path to where I am today." npr

trilobita

ikaite

Calcite after Ikaite (CaCO₃·6H₂O) var. Glendonite concretion.The rock was found at Kola Peninsula, Russia. Ikaite is a rare mineral that occurs in nature at temperatures up to 7°C in alkaline, phosphate-rich marine and continental waters. Although ikaite has generally been replaced by calcite (this replacement is called glendonite), it has preserved its original crystal shape. Because of the rather restricted conditions under which ikaite/glendonite forms, it serves as a marker for near-freezing water temperatures. Hydrohalite, a form of salt, precipitates at low temperatures from highly saturated brines. It is not well-preserved in sediments because of its high solubility, but its former existence can be inferred from the presence of halite or other minerals that preserve the shape of the original crystals. Minerals are just one of many proxies used by geologists to reconstruct past climates. Some minerals like ikaite define a very narrow set of conditions, while others, like the clays, appear in a number of geologic and climatic settings. Minerals along with other indicators — fossils, tree rings, pollen, ice cores, geochemistry or isotopes — provide tantalizing clues to ancient climates.

The giant cow that swam the ocean

Not so long ago, a sailor navigating the cold waters of the northern Pacific Ocean might have had every chance of been confronted by a giant cow.

This cow would have measured 10 metres long, and weighed between five and ten tonnes.

And it would have been the most adept swimmer, spending its days cruising the seas, grazing on fields of grass growing underwater.

The cow in question was known as Steller’s sea cow. It is now extinct, having left this earth almost 250 years ago.

A depiction of the now extinct Steller's sea cow (credit: Richard Ellis/SPL)

But many people are unaware that such a huge and extraordinary creature once existed, or know its incredible story.

And even today, scientists are still discovering fundamental insights into the life and history of this huge, lumbering, but almost mystical animal.

It belonged to a group of mammals, known as the Sirenia, named after the mermaids of Greek mythology that were known as sirens.

Today, four species of Sirenia still exist, grouped into two distinct families.

One, the dugong (Dugong dugon) of south-east Asia, measures some 3 metres long, weighing around 400 kg.

The dugong (Dugong dugon) of south-east Asia (credit: imageBROKER/Alamy)

There are also three species of manatee; the Amazonian manatee (Trichechus inunguis), the West Indian manatee (Trichechus manatus), and the West African manatee (Trichechus senegalensis). These can grow to 4 metres long and weigh almost 600 kg, and the three species of manatee are more closely related to each other than the dugong.

Amazonian manatee

West Indian Manatee

West African Manatee

All have large rotund bodies, downturned snouts, short rounded paddle-like flippers, and a horizontal tail fluke that they use to move around.

But Steller’s sea cow (Hydrodamalis gigas) was much, much bigger. It reached a length of 10 metres and different sources suggest it could have weighed anywhere between 4,000-11,000 kgs.

It also lacked teeth, surviving by using a pair of broad horny pads to chew kelp.

Surprisingly perhaps, the first recorded sighting of a Steller’s sea cow didn’t happen until 1741, when a sailing expedition led by Captain Vitus Bering of the Russian Navy was marooned on an desolate, treeless uninhabited island, later named Bering Island, in what is today known as the Bering Sea.

Those sailors that escaped Bering Island spread word of the bounty of meat to be found off its shores. Each year new expeditions hunted the animals.

One report stated that one sea cow could feed 33 men for a month, and it was thought sailors stored the meat on ships to feed themselves on voyages lasting up to a year.

Incredibly, the last sea cow was reported killed in 1768, just 27 years after the island and species had been discovered by modern man.

Scientists have since tried to establish whether these hunting expeditions killed off the sea cow, or whether other factors played a role.

A new genetic analysis, published in the journal Molecular Phylogenetics and Evolution, has now established which animal still living today is the closest relative of the Steller's sea cow.

A survey of the genes held in the nucleus of the animals’ cells confirms that dugongs, rather than manatees, are more closely related to Steller's sea cows.

The dugong now survives as the only truly herbivorous marine mammal, as manatees often frequent fresh water. bbc

Jurassic World: What do the paleontologists think?

Explaining the concept of this review is like explaining a dream. "I went to go see 'Jurassic World' before the film was in theaters, but instead of my friends, I brought two top paleontologists."

Based on a small sample size, the "Jurassic Park" film franchise has a special place in the heart of paleontologists. This is probably why I was able to convince the Smithsonian's National Museum of Natural History Director Kirk Johnson and Curator of Dinosauria Matthew Carrano, both paleontologists, to come to a screening of "Jurassic World."

The tl;dr of their reaction? "Jurassic World" is super entertaining — but it could have used more herbivores.

Here is the paleontologists' review, in the form of a condensed and edited conversation. There are, as you would imagine, mild — but not devastating — spoilers.

KJ: I did enjoy the addition of the Pterosaurs and the Mesosaur.

MC: Right, a few non-dinosaurs. That's true, having more than just peripheral role.

KJ: They definitely supercharged the Mesosaur and made the Pterosaurs way stronger than they would have been in real life.

MC: Yeah. Pterosours could do you damage, but it's hard to believe a Pterosaur could lift a person. They're not that strong. Their bones are like paper. It's hard to imagine not being able to get away from a Pterosaur. You could crush one, probably.

KJ: And their claws aren't like that.

MC: They're not eagles. That's the other thing, too. They're not actually animals that run around and grab things with their claws the way raptors do today. They're mouth predators. If they can't pick you up with their mouth, they're not going to eatyou. And a lot of Pterosaurs, their neck bones are not thick. They probably can't pick up a person. Their feet are not — I wouldn't imagine it to be the equivalent of an eagle. They basically are flat footed.

KJ: They're fishing.

MC: Bug eating. The average Pterosaur is much smaller. It's the same thing as the Velociraptor. And the Mesosaur is substantially larger than most Mesosaurs.

KJ: Twice-ish.

MC: Nice to see some marine things. Although I'd love to know how you get [a Mesosaur] out of a mosquito. How do you get the blood out of a sea creature out of a mosquito?

What's changed in dinosaur science between "Jurassic Park" and "Jurassic World"?

KJ: The number of dinosaurs we know has just, like, skyrocketed.

MC: Every six or seven weeks, you get a new dinosaur. And that pace has been going up for 20 years.

KJ: If you drive a direct connection between places putting value in dinosaurs and hiring dinosaur scientists, and then dinosaur science finding new dinosaurs, there's almost something like a direct cause and effect between something like "Jurassic Park" and this incredible number of new dinosaurs.

The new Jurassic World dinosaur is 'a little shy', apparently

Of all those newly discovered dinosaurs since the last installment of the series, which one should have been in "Jurassic World"?

KJ: Deinocheirus. A gigantic clawed duck thing. A lot of the cool weird ones are herbivores.

MC: Every single kind of carnivore is in there, right? With the herbivores, it's "we've got our horns one, we have our armor one, we have our longneck one, and we don't really care how many."

We've probably discovered about 4 percent of all the dinosaurs that ever existed. They should be just making these dinosaurs like "holy cow, what's that?" And they would all be dinosaurs you've never heard of. They could say, "Well it's kind of like a stegosaurus, but it's got all this other junk on it. I guess it's a ... " And they could just start naming new dinosaurs.

On the Indominus Rex, the made-up hybrid villain "dinosaur."

KJ: It basically looks like a supercharged Allosaurus. But it had bird raptor claws. Did you notice that? Those are eagle claws, they weren't dinosaur claws.

MC: And then it had sort of like a Bellusaur head with all these knobs on it.

KJ: It looks like a dinosaur, basically. It looked like you could easily find that.

MC: In the technical details no, but there are giant long-armed predatory dinosaurs. So you don't even need to get that weird about it. Interestingly, the color changing, that was in the book, the first book. There's a dinosaur in the first book called Carnotaurus. Which of course we don't know what color it was. But in the first "Jurassic Park" book, it was a color-changing dinosaur, which they only found out after they made it. It just turned out to be a camouflaged dinosaur. They got rid of it in the first movie originally, but they brought the concept back now.

On the film's choice to explain away the accuracy of "Jurassic World's" dinosaurs by saying that none of the park's creatures are "natural."

MC: I loved that, right? It was the "scientist, shut up" moment. B.D. Wong's character says something like: "You always wanted more teeth and more this, if we did it the way they were supposed to be they would look completely different." So the idea is, they don't have feathers on purpose. At least he provides an answer, right?

On the portrayal of scientists in the film.

KJ: This was the first one with no paleontologists in it?

MC: Yeah.

KJ: In the first (movie), there's the famous line, "I need the opinion of a paleobotanist." Which is the first and only time the word "paleobotany" has ever been uttered in a movie. As a paleobotanist I was —

MC: It was a high-water mark.

KJ: This one, there was, like, the tough guy who was the dinosaur trainer.

MC: But he was like an ex-Navy dude.

KJ: So that might be the big thing, is that they've matured past needing us.

What about the Jurassic plants?

KJ : My big pet peeve is of course, everybody short-shrifts the vegetation in the landscape. Everybody puts dinosaurs in modern landscapes. It's even worse if you call it "Jurassic World." All the implications are that you're going to build this entire world. But really it's not; it's Hawaii with dinosaurs. Dinosaurs didn't really live in the rain forest, because there weren't really rain forests to live in when dinosaurs were around.

MC: And actually if you had an island like that, if you assume that the dinosaurs could have adjusted to eating these things they've never eaten before, etc. It would have take no time at all for those dinosaurs to totally have remade that landscape, like elephants today. Elephants hate trees; they just start pulling them down. Elephants are engineering the landscape, and the big dinosaurs certainly would have done that. It wouldn't have been a dense rain forest for very long. They would have trashed the place.

What did you think about Chris Pratt's trained Velociraptors?

MC: Deeply unlikely, for a whole bunch of reasons. A lot of dinosaurs live in groups, it seems like. I'm sure there are ways of communicating, crocodiles do that today. But the raptors are engaging in wolf-like behavior. Even in mammals that stuff shows up late. It's a pretty new thing.

We want our predators to be as dramatic as possible, right? That whole notion actually came out of science, that they were pack hunters. That's not a movie invention. And it's based on the fact that the very first examples of these raptors that were found, there were several of them that were found together, and a plant eater that was much bigger. The idea was that it was a pack scenario. But that has not really held up in later years for a variety of reasons. But it's been a very catchy thing. The more likely thing is that they were running around eating lizards.

Copyright: Washington Post 

http://www.independent.co.uk/arts-entertainment/films/features/jurassic-world-what-do-the-paleontologists-think-10316292.html

he's probably thinking about forams

Fossil shows Prehistoric Reptile Gave Birth in Open Ocean

A case of mistaken identity turned out to be the key for proving that a prehistoric aquatic reptile did not lay eggs, but rather gave birth to live young in the warm seas of the Mesozoic.

Former Smithsonian pre-doctoral fellow and prehistoric bird expert Daniel Field, now a researcher at Yale University, was combing through the Yale Peabody Museum of Natural History’s collections of fossilized toothed birds. Coming to a box containing an unknown bird species, Field immediately recognized the bones had been misfiled.

Field saw the tiny jawbone pieces in the box—complete with teeth—and realized they very clearly belonged to a baby-sized version of a swimming reptile known as a mosasaur. Field had worked with adult mosasaur specimens during a paleontological dig earlier in his career.

What’s more, these specimens were collected from deposits from the prehistoric Bear Paw Sea, which once stretched from the Arctic to the Gulf of Mexico. That  gives strong credence to two previous proposals: that mosasaurs lived in the open ocean, not lurking exclusively near coastlines, as previously believed; and that they gave birth to live young.

“It really speaks to the value of the fossil record, that only the fossil record can provide direct evidence of the history of life,” Field says. “It helps us understand what these long-extinct animals would have been like as living, breathing creatures.”

Field added that the marine lizard’s reproductive strategy raises the question of whether mosasaurs and their like were truly cold-blooded in the classic sense. Giving birth to ready-to-swim young in the ocean doesn’t translate to being slow and sluggish like modern reptiles, Field notes.

Collected in Kansas in the late 1800s from the famous Niobrara Formation, the baby mosasaur bones strongly resemble the jaws of unrelated toothed birds in size and shape, and were found in an area where other fossilized birds had been collected. They’d probably been mistaken as bird bones simply due to their size.

Field’s expertise with birds and prior experience with mosasaurs enabled him to identify a distinguishing bulge on the jawbone samples, a structure absent in prehistoric toothed birds. The jawbones belong to a species of mosasaur called Clidastes. Adult specimens have been found 9 feet in length, but these jawbones came from babies no more than 12 inches long. 

Fossils of baby mosasaurs have been found before, but all were etched and pitted as if by acid, indicating they’d been transported to their final resting places in the belly of a predator. The Yale bones showed no such evidence, meaning they’d died of other causes. Field’s discovery fills a puzzling gap in the fossil record.

“Direct evidence of baby mosasaurs in an open marine setting had not yet been found, which is surprising because they had turned up for other groups of marine reptiles,” Field says.

Because of their body structure, researchers had suspected that mosasaurs did not haul themselves out onto a beach to lay eggs, similar to how sea turtles reproduce. Fossilized remains of other prehistoric swimmers, the ichthyosaurs, have been found in the process of giving birth. Some modern relatives of mosasaurs, including monitor lizards and some species of snakes, also skip the eggs.

Why are baby mosasaur fossils rare? Fields points to a variety of likely reasons, including collection bias. Turn-of-the-century fossil hunters were more interested in large, fearsome skeletons for their museums’ collections. They possibly disregarded smaller bones as uninteresting. Also, small-bodied organisms often aren’t preserved as well in the fossil record, due to factors including predation, scavenging, or the bones being smashed and scattered before they can fossilize.

“These fossils have basically waited in the bowels of the Yale Peabody museum for their time to shine,” Field laughed. “People talk about the second round of fossil hunting—everybody knows that paleontologists go into field to dig stuff up, but fossil hunting in museum collections can lead to new insights, too.”  smithsonianscience.si.edu

Field reported his findings in a recent issue of the journal Palaeontology.

DNA evidence suggests that the split between dogs and their wild ancestors occurred closer to 30,000 years ago

It looks like dogs might well have been man's (and woman's) best friend for a lot longer than once thought.

The long-held conventional wisdom is that canis lupus familiaris split from wolves 11,000 to 16,000 years ago and that the divergence was helped along by Stone Age humans who wanted a fellow hunter, a sentry and a companion.

Now, DNA evidence suggests that the split between dogs and their wild ancestors occurred closer to 30,000 years ago.

Publishing in Thursday's edition of Current Biology, the authors of a new study looked at the genome of a 35,000-year-old wolf from the Taimyr Peninsula in northern Siberia. "We find that this individual belonged to a population that diverged from the common ancestor of present-day wolves and dogs very close in time to the appearance of the domestic dog lineage," they wrote in the abstract.

The team, led by Pontus Skoglun, a research fellow at Harvard, concluded that the mutation rate for canines is "substantially slower than assumed by most previous studies, suggesting that the ancestors of dogs were separated from present-day wolves before the Last Glacial Maximum."

In other words, there may have been a faithful Fido walking with a human before the end of the last Ice Age (and before agriculture).

As The New York Times writes: "Based on the differences between the genome of the new species, called the Taimyr wolf, and the genomes of modern wolves and dogs, the researchers built a family tree that shows wolves and dogs splitting much earlier than the 11,000 to 16,000 years ago that a study in 2014 concluded."

However, a study reported in 2013 places the date of the canine split closer to the study published on Thursday. As NPR's Nell Greenfieldboyce reported then, a team headed by Robert Wayne, a biologist at the University of California, Los Angeles, and publishing in Science, used DNA analysis to peg the date at somewhere between 18,800 to 32,100 years ago.

In the new study, an author of the report was quoted by the Times as saying the simplest explanation for the new data is that dogs were domesticated as much as 30,000 years ago, but he cautions that the study does not prove it. "We can't just look at the DNA and say whether a canid was living with modern humans," he was quoted by the newspaper as saying.

"One scenario is that wolves started following humans around and domesticated themselves," Dalen told BBC. "Another is that early humans simply caught wolf cubs and kept them as pets and this gradually led to these wild wolves being domesticated. If this model is correct then dogs were domesticated by hunter gatherers that led a fairly nomadic lifestyle." npr

Earth's First Snake Likely Evolved On Land, Not In Water

Some scientists have speculated that snakes first evolved in water and that their long, slithery bodies were streamlined for swimming. But a new analysis suggests that the most recent common ancestor of all snakes actually lived on land.

This ancestral protosnake probably was a nocturnal hunter that slithered across the forest floor about 120 million years ago. And it likely had tiny hind limbs, left over from an even earlier ancestor, says Allison Hsiang, a researcher at Yale University.

"They probably weren't using them in locomotion in any way, but they did probably still have vestigial hind limbs stuck on the back of their bodies," Hsiang says.

The evolutionary origin of snakes has been a bit of a mystery for scientists, because the fossil record has an unfortunate dearth of snakes. "For a long time there weren't very good snake fossils," says Hsiang, who explains that researchers had not found "things that sort of told us what snakes looked like early on, or transitional fossils between snakes and their closest ancestors."

That's because snakes are mostly small, with fragile skeletons that aren't easily preserved — although there are some notable exceptions, such as Titanoboa, which lived 60 million years ago and could grow longer than 40 feet.

In the past decade, though, scientists have discovered a bunch of new snake fossils — some new species, as well as better-quality specimens of known species. "Previously, we just had, say, a few isolated vertebrae," says Hsiang, "which tells you it's a snake, but doesn't really tell you very much else."

The new fossils allowed Hsiang and some colleagues to do a rigorous, comprehensive analysis, to try to determine what the most recent common ancestor of all snakes might have been like. Besides fossils, the team studied the genes and anatomy of living snakes. "We had a total of 73 species, and I believe 15 of those were fossil species," says Hsiang.

Their analysis, described in the issue of BMC Evolutionary Biology published Tuesday, supports the idea of an early snake that slithered over the ground, and perhaps went into burrows to find food. "Snakes probably did not evolve, originally, to be in water," says Hsiang. "That's not why they developed this body plan; that's not what the earliest snakes were doing."

It looks like the ancestral snake had needle-like hooked teeth that it used to grab small, rodent-like critters, which it then swallowed whole. And it probably wouldn't have been able to eat anything much bigger than its own head. npr