Tag Archives: fossil

Mass Extinctions Reset the Long-Term Pace of Evolution

By Guest PostJuly 3, 2012Scienceandrew z krug, animal kingdom, birth rate, bivalve, chicago esque, david jablonski, evolution, evolutionary rate, fossil, fossil mollusk, jurassic period, maryland outcrop, mass extinction, oysters, pace of evolution, paleontologist, pleistocene epoch, richard bambach, scallops, species diversification, time boundaries, university of chicago

A new study indicates that mass extinctions affect the pace of evolution, not just in the immediate aftermath of catastrophe, but for millions of years to follow. The study’s authors, University of Chicago’s Andrew Z. Krug and David Jablonski, will publish their findings in the August issue of the journal Geology.

Scientists expected to see an evolutionary explosion immediately following a mass extinction, but Krug and Jablonski’s findings go far beyond that.

“There’s some general sense that the event happens, there’s some aftermath and then things return to normal,” said Krug, a research scientist in geophysical sciences at UChicago. But in reality, Krug said, “Things don’t return to what they were before. They operate at a different pace, sometimes more rapidly, other times more slowly. Evolutionary rates shift, and that shift is permanent until the next mass extinction.” (more…)

Ancient Giant Turtle Fossil Revealed

By Guest PostMay 18, 2012Nature, Scienceamazon river delta, ancient, behemoth, carbonemys cofrinii, carlos jaramillo, cerrejon formation, coal mine, coal turtle, Colombia, crocodiles, dan ksepka, edwin cadena, fossil, giant turtle, jonathan bloch, national science foundation, orinoco, paleontologist, pelomedusoides, reptiles, skull, south american giant, Titanoboa cerrejonensis

Picture a turtle the size of a Smart car, with a shell large enough to double as a kiddie pool. Paleontologists from North Carolina State University have found just such a specimen – the fossilized remains of a 60-million-year-old South American giant that lived in what is now Colombia.

The turtle in question is Carbonemys cofrinii, which means “coal turtle,” and is part of a group of side-necked turtles known as pelomedusoides. The fossil was named Carbonemys because it was discovered in 2005 in a coal mine that was part of northern Colombia’s Cerrejon formation. The specimen’s skull measures 24 centimeters, roughly the size of a regulation NFL football. The shell which was recovered nearby – and is believed to belong to the same species – measures 172 centimeters, or about 5 feet 7 inches, long. That’s the same height as Edwin Cadena, the NC State doctoral student who discovered the fossil. (more…)

Escalating Arms Race: Predatory Sea Urchins Drive Evolution

By Guest PostApril 18, 2012Natureasymmetrical, central europe, co evolution, escalation, escalation hypothesis, evolutionary arms race, evolutionary concept, fossil, geerat vermeij, lizard, macroevolutionary trend, mariusz a salamon, mesozoic crinoids, mesozoic diversity, mesozoic era, Nature, palaeontologist, paleobiology database, plankton, poland, predator, predator prey relationship, prey, przemyslaw gorzelak, sea lilies, sea urchins, sessile, tomasz baumiller, tug of war, university of michigan, university of silesia

ANN ARBOR, Mich.— Nature teems with examples of evolutionary arms races between predators and prey, with the predator species gradually evolving a new mode of attack for each defensive adaptation that arises in the prey species.

These adaptations are often portrayed as reciprocal, with prey and predator acting as two sides in an endless evolutionary tug of war known as co-evolution. (more…)

Burtele Foot Indicates Lucy Not Alone

By Guest PostMarch 30, 2012Scienceafar region, africa, alan deino, australopithecus afarensis, beverly z saylor, bones, bruce m latimer, burtele foot, early hominins, eastern africa, ethiopia, evolutionary history, famous fossil, fossil, geologic time, kenyan version, kenyanthropus platyops, late pliocene, lucy, middle awash valley, miocene apes, modern humans, mulugeta alene, naomi e levin, tim white, woranso mille, yohannes haile selassie

*Discovery of partial foot skeleton could mean hominin species lived side by side*

A new fossil discovery from Eastern Africa called the Burtele foot indicates Australopithecus afarensis, an early relative of modern humans, may not have been the only hominin to walk the plains and woodlands of what is now the Afar region of Ethiopia some 3.4 million years ago.

Researchers openly have questioned whether Au. afarensis, the species to which the famous fossil “Lucy” belongs, was the only living hominin during the late Pliocene of Africa. Lucy’s bones provided evidence that she and perhaps other early hominins may have walked upright, but whether or not she was the sole hominin species in her particular geologic time scale has been the subject of much debate. (more…)

Some Mammals Used Highly Complex Teeth to Compete With Dinosaurs

By Guest PostMarch 19, 2012Nature, Science3 d images, alistair evans, angiosperms, australia, back teeth, bumps, computed tomography, ct, cusps, dinosaur extinction, dinosaurs, event, extinction, finland, food, fossil, gregory p wilson, ian corfe, insect pollinators, jukka jernvall, mammal, mesozoic era, mikael fortelius, monash university, mountain range, multituberculates, Nature, paleontologist, peter smits, rodent, scanning, tooth surface, topography, tubercles, university of helsinki, university of washington, vince stricherz

Conventional wisdom holds that during the Mesozoic Era, mammals were small creatures that held on at life’s edges. But at least one mammal group, rodent-like creatures called multituberculates, actually flourished during the last 20 million years of the dinosaurs’ reign and survived their extinction 66 million years ago.

New research led by a University of Washington paleontologist suggests that the multituberculates did so well in part because they developed numerous tubercles (bumps, or cusps) on their back teeth that allowed them to feed largely on angiosperms, flowering plants that were just becoming commonplace. (more…)

Iridescent, Feathered Dinosaur Offers Fresh Evidence That Feathers Evolved to Attract Mates

By Guest PostMarch 9, 2012Scienceaerodynamic functions, anchiornis, archaeopteryx, austin, catapults, color, dinosaurs, evolution of feathers, feather pattern, feathers, fossil, four winged dinosaur, julia clarke, living birds, mark norell, mate attracting, matt shawkey, mick ellison, microraptor, modern birds, peking university, pigment, quanguo li, rui pei, thermoregulation, university of akron, university of texas, velociraptor

AUSTIN, Texas — A team of American and Chinese researchers has revealed the detailed feather pattern and color of Microraptor, a pigeon-sized, four-winged dinosaur that lived about 120 million years ago. A new specimen shows the dinosaur had a glossy iridescent sheen and that its tail was narrow and adorned with a pair of streamer feathers, suggesting the importance of display in the early evolution of feathers, as presented in the March 9 edition of the journal Science.

The research was conducted by scientists at the Beijing Museum of Natural History, Peking University, The University of Texas at Austin, the University of Akron, and the American Museum of Natural History. (more…)

Human’s Oldest Ancestor Found in Burgess Shale

By Guest PostMarch 6, 2012Scienceamerican palaeontologist, burgess shale, cambrian explosion, canada, charles doolittle walcott, chordate family, earthworms, fossil, jean bernard caron, leeches, marine organisms, myomeres, nerve cord, pikaia, pikaia gracilens, predator, primitive, primitive chordate, rom, royal ontario museum, scanning electron microscopy, simon conway morris, siphusauctum, tegopelte, university of cambridge, university of toronto, vascular system, vertebrate, worm, yoho national park

*Pikaia is most primitive vertebrate known*

Researchers from the University of Toronto, the Royal Ontario Museum (ROM) and the University of Cambridge have confirmed that a 505 million-year-old creature, found only in the Burgess Shale fossil beds in Canada’s Yoho National Park, is the most primitive known vertebrate and therefore the ancestor of all descendant vertebrates, including humans.

The research team’s analysis proves the extinct Pikaia gracilens is the most primitive member of the chordate family, the group of animals that today includes fish, amphibians, birds, reptiles and mammals. Their study is based on the analysis of 114 specimens and is published in the British scientific journal Biological Reviews. (more…)

Evolution of Earliest Horses Driven by Climate Change

By Guest PostFebruary 24, 2012Environment, Nature, Scienceaaron wood, atmosphere, bighorn basin, body size, cabin fork area, carbon, carbon dioxide, cause and effect, climate model, clydesdale, concentration, doug boyer, dwarfing phenomenon, earliest horse, evolution, florida museum of natural history, fossil, geochemical analysis, global temperature, h richard lane, horse teeth, industrial revolution, jonathan bloch, mammal, national science foundation, natural selection, North America, nsf, ocean, ornithologist, oxygen levels, paleocene-eocene thermal maximum, petm, prediction, ross secord, sifrhippus sandae, stephen chester, temperature, university of florida, university of nebraska lincoln, worland, yale

*The hotter it gets, the smaller the animal?*

When Sifrhippus sandae, the earliest known horse, first appeared in the forests of North America more than 50 million years ago, it would not have been mistaken for a Clydesdale.

It weighed in at around 12 pounds–and it was destined to get much smaller over the ensuing millennia.

Sifrhippus lived during the Paleocene-Eocene Thermal Maximum (PETM), a 175,000-year interval of time some 56 million years ago in which average global temperatures rose by about 10 degrees Fahrenheit. (more…)