Teen pregnancy the norm among dinosaurs

January 14

Dinosaurs descended from reptiles and evolved into today's birds, but their growth and sexual maturation were more like that of mammals - complete with teen pregnancy, according to a new study by University of California, Berkeley, scientists.

Though dinosaurs grew for much of their lives, they experienced a rapid growth spurt in adolescence, like mammals, said UC Berkeley graduate student Sarah Werning. She and Andrew H. Lee, a recent UC Berkeley Ph.D. recipient who is currently a postdoctoral fellow at Ohio University's College of Osteopathic Medicine in Athens, Ohio, have now shown that dinosaurs reached sexual maturity near the end of this rapid growth phase, well before reaching maximum body size. Medium-to-large mammals, including humans, also are able to reproduce before they finish growing.

Cross-section through the fossilized tibia or shinbone of a 150 million-year-old female Allosaurus skeleton, showing growth rings and the position of medullary bone laid down in the marrow cavity just prior to egg laying. This individual died when a 10-year-old adolescent, shortly before she would have laid her eggs. Silhouettes indicate the relative sizes of a juvenile and a fully-grown Allosaurus. (Andrew Lee/Ohio University; fossil courtesy of the University of Utah)

Complete article: Teen pregnancy the norm among dinosaurs

 

Paleontologist Discovers Soft Tissue in Dinosaur Bones

March 24

Conventional wisdom among paleontologists states that when dinosaurs died and became fossilized, soft tissues didn’t preserve – the bones were essentially transformed into “rocks” through a gradual replacement of all organic material by minerals. New research by a North Carolina State University paleontologist, however, could literally turn that theory inside out.

Dr. Mary Schweitzer, assistant professor of paleontology with a joint appointment at the N.C. Museum of Natural Sciences, has succeeded in isolating soft tissue from the femur of a 68-million-year-old dinosaur. Not only is the tissue largely intact, it’s still transparent and pliable, and microscopic interior structures resembling blood vessels and even cells are still present.

Branching vessels found in bone matrix of T. rex (A) and ostrich (B)

Complete article: NC State Paleontologist Discovers Soft Tissue in Dinosaur Bones

Abstract and Paper: Soft-Tissue Vessels and Cellular Preservation in Tyrannosaurus rex (Requires fee)

 

New meat-eating dinosaur duo from Sahara ate like hyenas, sharks

February 13

Credit: Todd Marshall

Two new 110 million-year-old dinosaurs unearthed in the Sahara Desert highlight the unusual meat-eaters that prowled southern continents during the Cretaceous Period. Named Kryptops and Eocarcharia in a paper appearing this month in the scientific journal Acta Palaeontologica Polonica, the fossils were discovered in 2000 on an expedition led by University of Chicago paleontologist Paul Sereno.

Short-snouted Kryptops palaios, or "old hidden face," was so named for the horny covering that appears to have covered nearly all of its face. "A fast, two-legged hyena gnawing and pulling apart a carcass," remarked co-author Steve Brusatte, "is how we might best imagine Kryptops’ dining habits." Like later members of its group (called abelisaurids) in South America and India, Kryptops had short, armored jaws with small teeth that would have been better at gobbling guts and gnawing on carcasses than snapping at live prey. About 25 feet in length, Kryptops was a voracious meat-eater.

A similar-sized contemporary, Eocarcharia dinops, or "fierce-eyed dawn shark," was so named for its blade-shaped teeth and prominent bony eyebrow. Unlike Kryptops, its teeth were designed for disabling live prey and severing body parts. Eocarcharia and kin (the carcharodontosaurids) gave rise to the largest predators on southern continents, matching or exceeding Tyrannosaurus in size. Eocarcharia’s brow was swollen into a massive band of bone, giving it a menacing glare.

Complete article: New meat-eating dinosaur duo from Sahara ate like hyenas, sharks (University of Chicago)

Abstract and Paper: Basal abelisaurid and carcharodontosaurid theropods from the Lower Cretaceous Elrhaz Formation of Niger (free)

 

"Amazing" Dinosaur Trove Discovered in Utah

June 17

Crowded with dinosaurs, petrified trees, and other prehistoric treasures, an ancient riverbed in Utah is surprising scientists.

The discovery sheds new light on a Jurassic landscape dominated by dinosaur giants that lived 145 to 150 million years ago.

In just three weeks of work on federal land near Hanksville, Utah, paleontologists say they unearthed at least two meat-eating dinosaurs, a probable Stegosaurus, and four sauropods—long necked, long-tailed plant-eaters that could reach 130 feet (40 meters) long, making them the largest animals ever to have walked the Earth.

"So far [the paleontologists] have found not only scattered bones but partial and complete skeletons. It's really amazing," said Scott Foss, a paleontologist in the Bureau of Land Management's (BLM's) Salt Lake City office.

Credit: Matthew Bonnan

Complete article: "Amazing" Dinosaur Trove Discovered in Utah

 

Albertonykus Borealis - America's Smallest Dinosaur

July 7

Albertonykus borealis, a slender bird-like creature is a new member of the family Alvarezsauridae and is one of only a few such fossils found outside of South America and Asia. In a paper published in the current issue of the journal Cretaceous Research, Longrich and University of Alberta paleontologist Philip Currie describe the specimen and explain how it it likely specialized in consuming termites by using its small but powerful forelimbs to tear into logs.

Abstract and Paper: Albertonykus borealis, a new alvarezsaur (Dinosauria: Theropoda) from the Early Maastrichtian of Alberta, Canada: implications for the systematics and ecology of the Alvarezsauridae (requires fee)

Picture credit: Todd Korol and Reuters

 

Fossil Feathers Preserve Evidence of Color

July 8

The traces of organic material found in fossil feathers are remnants of pigments that once gave birds their color, according to Yale scientists whose paper in Biology Letters opens up the potential to depict the original coloration of fossilized birds and their ancestors, the dinosaurs.

Closer study of a number of fossilized bird feathers by Yale PhD student Jakob Vinther revealed that organic imprints in the fossils — previously thought to be carbon traces from bacteria — are fossilized melanosomes, the organelles that contain melanin pigment.

Striped fossil feather and recent woodpecker feather. Under the scanning electron microscope there are melanosomes in the dark but not the light areas (left arrows) of the fossil. For comparison, melanosomes from a broken black feather and a white feather are shown (right arrows). [Credit: J.Vinther/Yale]

Complete article: Fossil Feathers Preserve Evidence of Color, Say Yale Scientists

 

Dinosaurs' "superiority" challenged by their crocodile cousins

11 September

Good luck, not general ‘superiority’, was the primary factor in the rise of the dinosaurs according to new research from the University of Bristol.

In a paper published in Science, Steve Brusatte and Professor Mike Benton challenge the general consensus among scientists that there must have been something special about dinosaurs that helped them rise to prominence.

Dinosaurs epitomize both success and failure. Failure because they went extinct suddenly 65 million years ago; success because they dominated terrestrial ecosystems for well over 100 million years evolving into a wide array of species that reached tremendous sizes.

A montage of the skulls of several crurotarsan archosaurs, the "crocodile-line" archosaurs that were the main competitors of dinosaurs during the Late Triassic period (230-200 million years ago). Dinosaurs and crurotarsans shared many of the same ecological niches, and some crurotarsans looked remarkably similar to dinosaurs. However, by the end of the Triassic period most crurotarsans were extinct, save for a few lineages of crocodiles, while dinosaurs weathered the storm and began a 135-million-year reign of dominance. Top (l-r): The rauisuchians Batrachotomus and Postosuchus; middle: the phytosaur Nicrosaurus and the aetosaur Aetosaurus; bottom: the poposauroid Lotosaurus and the ornithosuchid Riojasuchus.

Complete article: Dinosaurs' 'superiority' challenged by their crocodile cousins (Bristol University)

Abstract and Paper: Superiority, Competition, and Opportunism in the Evolutionary Radiation of Dinosaurs (Fee required)

 

New Tyrannosauroid from the UK

A partial postcranial skeleton from the Late Jurassic (Tithonian) of Dorset, England represents a new species of the theropod dinosaur Stokesosaurus, Stokesosaurus langhami. S. langhami is a member of Tyrannosauroidea, showing a distinct median vertical ridge on the lateral surface of the ilium, a prominent shelf medial to the preacetabular notch, a pronounced ischial tubercle, and a tibia that is elongate relative to the femur. One of only two definitive Jurassic tyrannosauroids known from more than isolated elements, it is the largest Jurassic tyrannosauroid reported to date and provides additional evidence for the presence of relatively small- or medium-sized basal tyrannosauroids in Asia, North America, and Europe during the Late Jurassic. The occurrence of Stokesosaurus in the Tithonian of the UK and USA and the absence of tyrannosauroids in contemporaneous west African faunas supports the hypothesis of a paleobiogeographic link during the Late Jurassic between North America and Europe, to the exclusion of Africa.

Abstract and Paper: New Information on Stokesosaurus, A Tyrannosauroid (Dinosauria: Theropoda) from North America and the United Kingdom (Fee required)

Picture credit: Todd Marshall

 

New meat-eating dinosaur from Argentina had bird-like breathing system

September 29

Credit: Todd Marshall

The remains of a new 10-meter-long predatory dinosaur discovered along the banks of Argentina's Rio Colorado is helping to unravel how birds evolved their unusual breathing system.

The discovery of this dinosaur builds on decades of paleontological research indicating that birds evolved from dinosaurs.

"Among land animals, birds have a unique way of breathing. The lungs actually don't expand," Sereno said. Instead, birds have developed a system of bellows, or air sacs, which help pump air through the lungs. It's the reason birds can fly higher and faster than bats, which, like all mammals, expand their lungs in a less efficient breathing process.

Discovered by Paul Sereno and his colleagues in 1996, the new dinosaur is named Aerosteon riocoloradensis ("air bones from the Rio Colorado"). "Aerosteon, found in rocks dating to the Cretaceous period about 85 million years old, represents a lineage surviving in isolation in South America. Its closest cousin in North American, Allosaurus, had gone extinct millions of years earlier and was replaced by tyrannosaurs."

Complete article: New meat-eating dinosaur from Argentina had bird-like breathing system (University of Chicago)

Abstract and Paper: Evidence for Avian Intrathoracic Air Sacs in a New Predatory Dinosaur from Argentina (Free)

 

Dinosaur nasal appraisal

October 29

Scientists at the University of Calgary and the Royal Tyrrell Museum are providing new insight into the sense of smell of carnivorous dinosaurs and primitive birds in a research paper published in the British journal Proceedings of the Royal Society B. The study, by U of C paleontologist Darla Zelenitsky and Royal Tyrrell Museum curator of dinosaur palaeoecology François Therrien, is the first time that the sense of smell has been evaluated in prehistoric meat-eating dinosaurs. They found that Tyrannosaurus rex had the best nose of all meat-eating dinosaurs, and their results tone down the reputation of T. rex as a scavenger.

Complete article: T. rex "followed its nose" while hunting (University of Calgary)

Picture credit: Mineo Shiraishi

 

Paleontologists Doubt "Dinosaur Dance Floor"

November 8

A group of paleontologists visited the northern Arizona wilderness site nicknamed a "dinosaur dance floor" and concluded there were no dinosaur tracks there, only a dense collection of unusual potholes eroded in the sandstone.

So the scientist who leads the University of Utah's geology department says she will team up with the skeptics for a follow-up study.

"Science is an evolving process where we seek the truth," says Marjorie Chan, professor and chair of geology and geophysics, and co-author of a recent study that concluded the pockmarked, three-quarter-acre site in Vermilion Cliffs National Monument was a 190-million-year-old dinosaur "trample surface".

 

University of Utah geologist Winston Seiler walks among hundreds of what appear to be dinosaur footprints in a "trample surface" that likely was a watering hole amid desert sand dunes during the Jurassic Period 190 million years ago. The track site, which also appears to include some dinosaur tail-drag marks, is located in Coyote Buttes North area along the Arizona-Utah border. (Photo: Roger Seiler)

 

"Bizarre" New Dinosaur: Giant Raptor Found in Argentina

December 16

 

Scientists have discovered what they say is a completely unexpected new giant dinosaur that lived 70 million years ago in Argentina.

At 16.5 to 21 feet long (5 to 6.5 meters) long, depending on its tail size, Austroraptor cabazai is among the largest of the slender, carnivorous, two-legged dinosaurs called raptors, said Fernando Novas, the lead researcher behind the discovery.

The dinosaur's incomplete skeleton — including head, neck, back, and foot bones—was extracted from rocks in the far-southern Patagonia region.

Novas and colleagues were able to virtually reconstruct Austroraptor's complete skeleton, by using the dinosaur's closest relatives as references, said Novas, who received funding for his work from the National Geographic Society's Committee for Research and Exploration.

Complete article: "Bizarre" New Dinosaur: Giant Raptor Found in Argentina

Abstract and Paper: A bizarre Cretaceous theropod dinosaur from Patagonia and the evolution of Gondwanan dromaeosaurids

Picture credit: Rodrigo Vega