Dinosaurs extinct, birds survived


Dinosaurs, birds and extinction. Timeline adapted from S.L. Brusatte, J.K. O’Connor and E.D. Jarvis/current biol. 2015

From Science News:

Some lucky birds escaped dino doomsday

Feathers, wishbones and more were a dino thing before they were a bird thing

By Susan Milius

2:30pm, January 25, 2017

The flight stuff

Some traits made famous by modern birds first popped up in dinosaurs that met unfortunate ends. This diagram shows when traits like standing on two legs, feathers and wishbones emerged in the bird/dino part of the tree. Numbers one through four correspond to examples of trailblazing birdlike dinosaurs and early birds highlighted in the interactive slideshow below.

The asteroid strike (or was it the roiling volcanoes?) that triggered dino doomsday 66 million years ago also brought an avian apocalypse. Birds had evolved by then, but only some had what it took to survive.

Biologists now generally accept birds as a kind of dinosaur, just as people are a kind of mammal. Much of what we think of as birdlike traits — bipedal stance, feathers, wishbones and so on — are actually dinosaur traits that popped up here and there in the vast doomed branches of the dino family tree. In the diagram above, based on one from paleontologist Stephen Brusatte of the University of Edinburgh and colleagues, anatomical icons give a rough idea of when some of these innovations emerged.

One branch of the dinosaur tree gradually turned arguably avian (in the Avialae/Aves group) by about 165 million to 150 million years ago. That left plenty of time for bona fide birds to diversify before the great die-off.

The bird pioneers included the once widespread and abundant Enantiornithes, or “opposite birds.” Compared with modern birds, their ball-and-socket shoulder joints were “backwards,” with ball rather than socket on the scapula.

These ancient alt birds may have gone down in the big extinction that left only fish, amphibians, mammals and a few reptile lineages (including birds) among vertebrates. There’s not a lot of information to go on. “The fossil record of birds is pretty bad,” Brusatte says. “But I think those lineages that go up to the red horizontal line of doom in my figure are ones that died in the impact chaos.”

Dinosaur age lizard discovery


This video from the USA says about itself:

3 June 2013

A team of U.S. paleontologists, led by Jason Head of the University of Nebraska-Lincoln, describes fossils of the giant lizard from Myanmar in the scientific journal Proceedings of the Royal Society B. Their analysis shows that it is one of the biggest known lizards ever to have lived on land.

At almost six feet long and weighing upwards of 60 pounds, the lizard provides new and important clues on the evolution of plant-eating reptiles and their relationship to global climate and competition with mammals.

From the University of Washington in the USA:

24 January 2017

Prized fossil find illuminates the lives of lizards in the Age of Dinosaurs

Paleontologists picking through a bounty of fossils from Montana have discovered something unexpected — a new species of lizard from the late dinosaur era, whose closest relatives roamed in faraway Asia.

This ancient lizard, which lived 75 million years ago in a dinosaur nesting site, is described from stem to stern in a paper published Jan. 25 in the Proceedings of the Royal Society B. Christened Magnuviator ovimonsensis, the new species fills in significant gaps in our understanding of how lizards evolved and spread during the dinosaur era, according to paleontologists at the University of Washington and the Burke Museum of Natural History & Culture who led the study.

“It is incredibly rare to find one complete fossil skeleton from a relatively small creature like this lizard,” said David DeMar, lead author and postdoctoral research associate in the UW biology department and the Burke Museum. “But, in fact, we had two specimens, both from the same site at Egg Mountain in Montana.”

Right out of the gate, Magnuviator is reshaping how scientists view lizards, their biodiversity and their role in complex ecosystems during this reptile’s carefree days in the Cretaceous Period 75 million years ago.

Based on analyses of the nearly complete fossil skeletons, Magnuviator was an ancient offshoot of iguanian lizards — and they’re actually the oldest, most complete iguanian fossils from the Americas. Today, iguanians include chameleons of the Old World, iguanas and anoles in the American tropics and even the infamous water-walking basilisk — or “Jesus Christ” — lizards. But based on its anatomy, Magnuviator was at best a distant relative of these modern lizard families, most of which did not arise until after the non-avian dinosaurs — and quite a few lizards and other creatures — went extinct 66 million years ago.

The team came to these conclusions after meticulous study of both Egg Mountain specimens over four years. This included a round of CT scans at Seattle Children’s Hospital to narrow down the fossil’s location within a larger section of rock and a second round at the American Museum of Natural History to digitally reconstruct the skull anatomy. The fact that both skeletons were nearly complete allowed them to determine not only that Magnuviator represented an entirely new species, but also that its closest kin weren’t other fossil lizards from the Americas. Instead, it showed striking similarities to other Cretaceous Period iguanians from Mongolia.

“These ancient lineages are not the iguanian lizards which dominate parts of the Americas today, such as anoles and horned lizards,” said DeMar. “So discoveries like Magnuviator give us a rare glimpse into the types of ‘stem’ lizards that were present before the extinction of the dinosaurs.”

But Magnuviator’s surprises don’t end with the Mongolian connection. The site of its discovery is also eye-popping.

Egg Mountain is already famous among fossil hunters. Over 30 years ago, paleontologists discovered the first fossil remains of dinosaur babies there, and it is also one of the first sites in North America where dinosaur eggs were discovered.

“We now recognize Egg Mountain as a unique site for understanding Cretaceous Period ecosystems in North America,” said senior author Greg Wilson, UW associate professor of biology and curator of paleontology at the Burke Museum. “We believe both carnivorous and herbivorous dinosaurs came to this site repeatedly to nest, and in the process of excavating this site we are learning more and more about other creatures who lived and died there.”

The team even named their new find as homage to its famous home and its close lizard relatives in Asia. Magnuviator ovimonsensis means “mighty traveler from Egg Mountain.”

Through excavations at Egg Mountain led by co-author David Varricchio at Montana State University and meticulous analysis of fossils at partner institutions like the UW and the Burke Museum, scientists are piecing together the Egg Mountain ecosystem of 75 million years ago. In those days, Egg Mountain was a semi-arid environment, with little or no water at the surface. Dinosaurs like the duck-billed hadrosaurs and the birdlike, carnivorous Troodon nested there.

Researchers have also unearthed fossilized mammals at Egg Mountain, which are being studied by Wilson’s group, as well as wasp pupae cases and pollen grains from plants adapted for dry environments. Based on the structure of Magnuviator’s teeth, as well as the eating habits of some lizards today, the researchers believe that it could have feasted on wasps at the Egg Mountain site. Though based on its relatively large size for a lizard — about 14 inches in length — Magnuviator could have also eaten something entirely different.

“Due to the significant metabolic requirements to digest plant material, only lizards above a certain body size can eat plants, and Magnuviator definitely falls within that size range,” said DeMar.

Whatever its diet, Magnuviator and its relatives in Mongolia did not make it into the modern era. DeMar and co-authors hypothesize that these stem lineages of lizards may have gone extinct along with the non-avian dinosaurs. But given the spotty record for lizards in the fossil record, it will take more Magnuviator-level discoveries to resolve this debate. And, unfortunately, part of the excitement surrounding Magnuviator is that it is a rare find.

Other co-authors are the late Jack Conrad of the New York Institute of Technology and the American Museum of Natural History and Jason Head of the University of Cambridge. The research was funded by the National Science Foundation and the American Museum of Natural History.

Dinosaur age bird’s colour research


Eoconfuciusornis zhengi reconstruction

From Science News:

Cretaceous bird find holds new color clue

First evidence of pigment pods embedded in keratin found in fossil feathers

By Meghan Rosen

3:30pm, November 21, 2016

A 130-million-year-old bird holds a clue to ancient color that has never before been shown in a fossil.

Eoconfuciusornis’ feathers contain not only microscopic pigment pods called melanosomes, but also evidence of beta-keratin, a protein in the stringy matrix that surrounds melanosomes, Mary Schweitzer and colleagues report November 21 in the Proceedings of the National Academy of Sciences.

Together, these clues could strengthen the case for inferring color from dinosaur fossils, a subject of debate for years (SN: 11/26/16, p. 24). Schweitzer, a paleontologist at North Carolina State University in Raleigh, has long pointed out that the microscopic orbs that some scientists claim are melanosomes may actually be microbes. The two look similar, but they have some key differences. Microbes aren’t enmeshed in keratin, for one.

In Eoconfuciusornis’ feathers, Schweitzer and colleagues found round, 3-D structures visible with the aid of an electron microscope. And a molecular analysis revealed bundles of skinny fibers, like the filaments of beta-keratin in modern feathers. The authors don’t speculate on the bird’s color, but they do offer a new way to support claims for ancient pigments.

“Identifying keratin is key to ruling out a microbial source for microbodies identified in fossils,” they write.

Oviraptor dinosaur discovery in China


This video from China ays about itself:

10 November 2016

A newly discovered species of dinosaur has been identified from an extraordinarily complete fossil almost destroyed by dynamite.

Preserved raising its beaked head, with feathered wings outstretched, in the mud it was mired in when it died 72 million years ago, it was one of the last surviving dinosaurs in Asia.

From Science News:

Dragon dinosaur met a muddy end

Feathered oviraptorosaurs surged at the end of the age of dinosaurs

By Meghan Rosen

9:00am, November 10, 2016

A bizarre new birdlike dino was part of an evolutionary extravaganza at the end of the age of dinosaurs. And it was a real stick-in-the-mud, too.

Construction workers blasted Tongtianlong limosus out of the Earth near Ganzhou in southern China. “They very nearly blew this thing to smithereens,” says paleontologist Stephen Brusatte of the University of Edinburgh in Scotland.

The find is one of six oviraptorosaur species discovered from roughly the same place and time — around 72 million to 66 million years ago. Like its feathered cousins, Tongtianlong walked on two legs and had a sharp beak. But each species had distinct skeletal quirks.

Tongtianlong, for one, had a bony, domelike crest on its skull. Oviraptorosaurs were churning out lots of new species during the last stage of the Cretaceous Period, Brusatte says. Tongtianlong was part of “the final wave of dinosaur diversification before the asteroid came down and ended everything.”

This particular fossilized animal lies in a bed of reddish-purple mudstone, preserved in an unusually awkward position: head stuck out, neck arched, wings outspread. It may have died after a desperate struggle to free itself from mud, researchers suggest November 10 in Scientific Reports. That’s actually how the dinosaur gets its name: Tongtianlong limosus is a mix of Chinese Pinyin and Latin meaning “muddy dragon on the road to heaven.”

Valdosaurus dinosaur, well-preserved fossil found in England


This video says about itself:

2 September 2015

Dryosaurus” is a genus of an ornithopod dinosaur that lived in the Late Jurassic period. It was an iguanodont. Fossils have been found in the western United States, and were first discovered in the late 19th century. “Valdosaurus canaliculatus” and “Dysalotosaurus lettowvorbecki” were both formerly considered to represent species of “Dryosaurus”.

“Dryosaurus” had a long neck, long, slender legs and a long, stiff tail. Its arms, however, with five fingers on each hand, were short. Known specimens were about 8 to 14 feet long and weighed 170 to 200 pounds. However, the adult size is unknown, as no known adult specimens of the genus have been found.

“Dryosaurus” had a horny beak and cheek teeth and, like other ornithopods, was a herbivore. Some scientists suggest that it had cheek-like structures to prevent the loss of food while the animal processed it in the mouth.

A quick and agile runner with strong legs, “Dryosaurus” used its stiff tail as a counterbalance. It probably relied on its speed as a main defense against carnivorous dinosaurs.

The teeth of “Dryosaurus” were, according to museum curator John Foster, characterized by “a strong median ridge on the lateral surface.” “Dryosaurus” subsisted primarily on low growing vegetation in ancient floodplains.

A “Dryosaurus” hatchling found at Dinosaur National Monument in Utah confirmed that “Dryosaurus” followed similar patterns of craniofacial development to other vertebrates; the eyes were proportionally large while young and the muzzle proportionally short. As the animal grew, its eyes became proportionally smaller and its snout proportionally longer.

By Pete Buchholz in Britain:

A specimen of the dryosaurid Valdosaurus has been discovered on the Isle of Wight

The most complete specimen of the poorly known dryosaurid Valdosaurus canaliculatus has been discovered in Lower Cretaceous rocks on the Isle of Wight. This new discovery helps flesh out the anatomy of this dinosaur and is one of the most complete dinosaur specimens known from England.

The Isle of Wight off the south coast of England is a fossil-hunter’s paradise. Rocks of the Wessex Formation, deposited during the Early Cretaceous, approximately 130 million years ago, are exposed in numerous locations across the island. The Wessex Formation preserves numerous fish, turtles, crocodilians, and pterosaurs. It also has a rather famous dinosaur fauna, including the spinosaurid Baryonyx, the early tyrannosaur Eotyrannus, a number of fragmentary sauropods, and the ornithopods Iguanodon, Mantellisaurus, Hypsilophodon, and Valdosaurus.

Noisy dinosaur age bird discovered in Antarctic


This video says about itself:

Discovery of fossil “voice box” of Antarctic bird suggests dinosaurs couldn’t sing

2 October 2016

Researchers have found the oldest known fossil vocal organ of a bird … in Antarctica. The voice box is from a species related to ducks and geese that lived during the age of dinosaurs more than 66 million years ago. A National Science Foundation funded team led by the University of Texas at Austin discovered the ancient vocal organ called a syrinx–and its apparent absence from non-bird dinosaur fossils of the same age. Researchers believe the organ may have originated late in the evolution of birds after the origin of flight. Drawing on their research, team leader Julia Clarke said that other dinosaurs may not have been able to make noises similar to modern bird calls, but most likely made closed-mouth sounds similar to ostrich booms that don’t require a syrinx.

The organ was found in a fossil species called Vegavis iaai. The fossil was discovered in 1992 on Vega Island in the Antarctic Peninsula by a team from the Argentine Antarctic Institute. It was named in 2005 by Clarke and Argentine colleagues. But, it wasn’t until 2013 Clarke discovered the fossil syrinx in the new specimen and began analysis. The international team may figure out what dinosaurs sounded like, gaining insight into the origins of bird song. The findings appear in the October 12 issue of “Nature”.

See also here.

From Science News:

Birds’ honks filled Late Cretaceous air

Sounds inferred from oldest preserved avian voice box

By Meghan Rosen

3:53pm, October 12, 2016

ANCIENT VOICE BOX: A ducklike bird that lived some 68 million to 66 million years ago left behind fossilized remains of a voice box, or syrinx, on an island off the coast of Antarctica.

Some ancient birds may have sounded like honking ducks.

For the first time, scientists have discovered the fossilized remains of a voice box from the age of the dinosaurs. The sound-making structure, called a syrinx, belonged to Vegavis iaai, a bird that lived 68 million to 66 million years ago, researchers report October 12 in Nature.

“It may be a once-in-a-lifetime discovery,” says evolutionary biologist Patrick O’Connor of Ohio University in Athens, who wrote a commentary in Nature about the fossil. Now, he says, the hunt will be on to find voice boxes in other fossils.

The new work helps fill in the soundscape of the Late Cretaceous Epoch. It could also offer hints about sounds made by all sorts of dinosaurs, says study coauthor Julia Clarke of the University of Texas at Austin.

Unlike in humans, where the larynx lies below the throat, birds’ voice boxes rest inside the chest at the base of the windpipe. Stacked rings of cartilage anchor vibrating membranes that make sound when air whooshes through.

This delicate structure doesn’t typically fossilize. In fact, scientists have previously spotted just a few syrinxes in the fossil record. The oldest known, from a wading bird, was about 50 million years old. Clarke’s team examined that syrinx, which hadn’t been studied before, and the one from V. iaai.

The V. iaai fossil, a partial skeleton discovered on an island off the coast of Antarctica, was removed from a rock about the size of a cantaloupe, Clarke says. Just one small area remained encased in rocky material. Everyone thought that bit was trivial, she says. But “it was within that tiny little section that I saw the syrinx.” Three-dimensional CT scans let her peer within the rock and see the telltale rings of a voice box, a structure roughly half the size of a multivitamin pill. “It was one of the biggest, happiest days of my career,” Clarke says.

Biologist Philip Senter of Fayetteville State University in North Carolina, who was not involved in the study, echoes Clarke’s enthusiasm. “It’s quite exciting to find such a rarely preserved structure,” he says. Seeing it in 3-D will make paleontologists “chortle joyously.”

Comparing the fossil with living birds helped Clarke and her team figure out what sounds the ancient bird might have made. Both the bird’s skeleton and its syrinx suggest it squawked like today’s ducks and geese.

The find also proves that voice boxes from dinosaurs’ time can indeed fossilize. No one has found the structures in nonavian dinosaurs, Clarke says. “That suggests that most dinosaurs may not have had a syrinx.”

Instead, she proposes, dinosaurs like Tyrannosaurus rex and Stegosaurus might have made noises like crocodiles: deep “booming” sounds generated in the back of the mouth.

Small Cretaceous pterosaurs discovered


This video says about itself:

25 July 2014

Pterosaurs (/ˈtɛrɵsɔr/, from the Greek πτερόσαυρος, pterosauros, meaning “winged lizard”) were flying reptiles of the clade or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period (228 to 66 million years ago).

Pterosaurs are the earliest vertebrates known to have evolved powered flight. Their wings were formed by a membrane of skin, muscle, and other tissues stretching from the ankles to a dramatically lengthened fourth finger. Early species had long, fully toothed jaws and long tails, while later forms had a highly reduced tail, and some lacked teeth. Many sported furry coats made up of hair-like filaments known as pycnofibers, which covered their bodies and parts of their wings. Pterosaurs spanned a wide range of adult sizes, from the very small Nemicolopterus to the largest known flying creatures of all time, including Quetzalcoatlus and Hatzegopteryx.

From Science News:

Pterosaurs weren’t all super-sized in the Late Cretaceous

Some of the flying reptiles were smaller than a bald eagle

By Meghan Rosen

7:00am, September 12, 2016

Pterosaurs didn’t have to be gargantuan to survive in the Late Cretaceous.

Fragmentary fossils of a roughly 77-million-year-old pterosaur found in British Columbia suggest it had a wingspan of just 1.5 meters, about a quarter that of a bald eagle.

Bald eagles have wingspans of about two meters. So, the newly discovered pterosaus were smaller than bald eagles; but not four times smaller.

The ancient flier is the smallest pterosaur discovered during this time period — by a lot, report paleontologist Elizabeth Martin-Silverstone of the University of Southampton in England and colleagues August 30 in Royal Society Open Science.

Dozens of larger pterosaurs, some with wings spanning more than 10 meters (nearly the length of a school bus), have been unearthed. But until now, scientists had found only two small-scale versions, with wingspans 2.5 to 3 meters long, from the period stretching from 66 million to 100 million years ago.

Some scientists blamed competition with birds for the scarcity of little flying reptiles. Researchers have proposed that, “the only way pterosaurs could survive was by evolving completely crazy massive sizes,” Martin-Silverstone says.

The new find, she says, may mean that, “pterosaurs were doing better than we thought.”