Maelestes & the Origin of Placental Mammals

Cretaceous eutherians and Laurasian origin for placental mammals near the K/T boundary. 2007. J. R. Wible, et al. Nature 447: 1003-1006.

Abstract: Estimates of the time of origin for placental mammals from DNA studies span nearly the duration of the Cretaceous period (145 to 65 million years ago), with a maximum of 129 million years ago and a minimum of 78 million years ago.

Maelestes gobiensis

Palaeontologists too are divided on the timing. Some support a deep Cretaceous origin by allying certain middle Cretaceous fossils (97–90 million years old) from Uzbekistan with modern placental lineages, whereas others support the origin of crown group Placentalia near the close of the Cretaceous. This controversy has yet to be addressed by a comprehensive phylogenetic analysis that includes all well-known Cretaceous fossils and a wide sample of morphology among Tertiary and recent placentals.

Here we report the discovery of a new well-preserved mammal, Maelestes gobiensis, from the Late Cretaceous of Mongolia and a broad-scale phylogenetic analysis. Our results exclude Cretaceous fossils from Placentalia, place the origin of Placentalia near the Cretaceous/Tertiary (K/T) boundary in Laurasia rather than much earlier within the Cretaceous in the Southern Hemisphere, and place afrotherians and xenarthrans in a nested rather than a basal position within Placentalia.

Off To The Field

It's that time of year again. I head out tomorrow for field work in Alberta and then from there to the Gobi for a good chunk of August and Sept. After that it's the Horned-Dino conference in Drumheller so I should be back at the CMNH sometime around the end of September. As time and computer access allows I'll post updates and photos, but as for previous summers postings will be light until I return.

Lego Albertaceratops

From the Edmonton Journal:

Lego brick-master Robin Sather was commissioned by the Telus World of Science to build the Albertaceratops head for its feature exhibit, Lost Worlds: From Dinosaurs to Ancient Civilizations.

Paleontologists think the creature was an evolutionary middle-step or intermediate between older, larger-horned dinosaurs and their small-horned descendants. "I've tried to incorporate that into the design," Sather said.

With help from Ryan and the Royal Tyrrell Museum, Sather spent about two months researching and perfecting his Albertaceratops design.

The head is about two-and-a-half metres high and more than a metre-and-a-half wide, both from side to side and front to back. He is one of only a handful of Lego Certified Professionals worldwide, adult hobbyists who have a formal working relationship with Lego but are not employed by the company.

When the dinosaur exhibit ends in September, children will be invited to dismantle Sather's Lego creation, rendering the Albertaceratops once again extinct.

The Telus World of Science Lost Worlds exhibit -- developed in co-operation with the Royal Tyrrell Museum of Paleontology -- opened on Saturday and runs until Sept. 3. It is designed to explore events that led to the extinction of the dinosaurs and the downfall of several ancient civilizations.

The paleontologist who discovered the Albertaceratops (me!) will give a presentation at 2 p.m. on Saturday at the Telus World of Science.

ROM Fossils Make Way For $270 Million Dollar Crystal

From the London Free Press:

Thanks to a $270-million addition to the Royal Ontario Museum, the University of Western Ontario has acquired the Toronto museum's collection of fossils from the Mazon Creek area, located west of Chicago. The site is known for producing well-preserved fossils of jellyfish, fish, marine crustaceans, insects and plants.

ROM with new crystal addition

The fossils were stored in buckets on the ROM's roof to take advantage of the freeze-thaw cycle, which cracks the rocks open and, after time, exposes the fossils. When work on the much-hype Michael Lee-Chin Crystal, moved to the downtown Toronto museum's north side, engineers asked the fossil rocks be moved from the roof.

"We came to a mutually beneficial solution with the folks at the ROM," says Matt Devereux, outreach co-ordinator for Western's science faculty. "We drove to Toronto and picked up three tonnes of these rocks and brought them back to London . . . we'll be treasure hunting for a few years by the looks of it."

Devereux says the pair have only scanned the tops of the buckets and have already discovered fossils of Tullimonstrum gregarium, also known as the Tully Monster, jellyfish, shrimp, polychete worms and various plants.

SVP 2008 In Cleveland

Logo by William Stout

FYI, the 2008 Society of Vertebrate Paleontology meeting will be right here in Cleveland, Ohio. SVP member and artist-extraordinaire, Bill Stout, came through in a pinch and did the logo for us--you should be seeing this shortly in the 2nd circular for the 2007 meeting. For more details go to the recently revamped SVP site.

The War That Time Forgot

Our friends over at Atomic Surgery present the first part of a story from 'The War That Time Forgot'!

The Palaeozoic Ancestry of Salamanders, Frogs and Caecilians

The Palaeozoic Ancestry of Salamanders, Frogs and Caecilians. 2007. Robert L. Carroll. Zoological Journal of the Linnean Society 150: 1-140.

Triadobatrachus massinoti, a primitive frog-like amphibian from the Lower Triassic of Madagascar by Pavel Říha

Abstract [edit]: The relationships of frogs, salamanders, and caecilians (Gymnophiona) with one another and with the vast assemblage of Palaeozoic amphibians remain highly contentious phylogenetic problems. Cladistic analyses support a common ancestry of the three modern orders, but fail to achieve a consensus regarding their affinities with Palaeozoic amphibians.

Making use of the numerous derived characters that are expressed in either the larvae or adults of extant salamanders, frogs, and caecilians provides the basis for recognizing a nested sequence of synapomorphies that support a common ancestry of salamanders and anurans with temnospondyl labyrinthodonts to the exclusion of caecilians. The larvae of Carboniferous and Permian temnospondyl labyrinthodonts provide strong evidence for their being members of the stem group of urodeles. This is based primarily on the great similarity in the sequence of ossification of the bones of the skull and appendicular skeleton, but is also supported by detailed similarities of the hyoid apparatus.

Recognition of a sister-group relationship between Permo-Carboniferous branchiosaurids and crown-group salamanders makes it possible to determine the sequence of changes in the anatomy and ways of life that occurred during the origin of urodeles, and to determine their time of divergence relative to that of frogs and caecilians.

Anyone with an interest in the evolutionary history of amphibians will want to get a copy of Bob Carroll’s latest monograph.

Pre-Mesozoic Pangea

Pooch Cafe by Paul Gilligan

Oldest Mushroom Found In Amber

Evidence of mycoparasitism and hypermycoparasitism in Early Cretaceous amber. 2007. Ge. O. Poinar Jr. and R. Buckley. Mycological Research 111: 503-506.

From Virginia Gewin at News@nature.com:

George Poinar, an Oregon State University zoologist and president of The Amber Institute, in Corvallis, Oregon, and Ron Buckley, a registered nurse and amateur fossil hunter from Florence, Kentucky have found the oldest mushroom fossil yet, encased in amber along with a striking example of a parasite feeding upon a parasite. Dated to 100 million years ago by the age of material surrounding the amber, the mushroom joins the exclusive company of just a handful of fossilized fleshy fungal bodies ever found.

The amber also holds the remains of an ancient parasitic relationship. The sample contains a mycoparasite, or fungus growing on the mushroom, and a hyperparasite growing on the mycoparasite.

Buckley's amber fascination is also a money-making venture. He sells collectable pieces with trapped bugs or flowers on eBay, an online auction website. Over time, he's honed a sharp eye for pieces of scientific interest — which he sends to Poinar. So far, they say they have discovered the oldest-known bee, the oldest-known flowers in amber and the oldest-known ticks. Their oldest find yet is a 130 million-year-old nematode parasite of a fly.

Born This Day: George Gaylord Simpson

June 16, 1902 - Oct 6, 1984.

"Life is the most important thing about the world, the most important thing about life is evolution. Thus, by consciously seeking what is most meaningful, I moved from poetry to mineralogy to paleontology to evolution." G.G. Simpson

From the web site supporting the excellent PBS show “Evolution”:

As one of the founders of the "modern synthesis" of evolution, paleontologist George Gaylord Simpson argued that the fossil record supports Darwin's theory that natural selection acting on random variation in a population is the driving force behind evolution. Simpson was among the first to use mathematical methods in paleontology, and he also took into account newly discovered genetic evidence for evolution in his study of paleontology. In his 1944 book, Tempo and Mode in Evolution, Simpson divided evolutionary change into "tempo," the rate of change, and "mode," the manner or pattern of change, with tempo being a basic factor of mode. Simpson saw paleontology, revealing the long history of life on earth, as a unique field through which to study the history of evolution.

The early part of the twentieth century saw evolutionary theory embattled by disagreements over Darwin's emphasis on natural selection. The then-newly rediscovered work of Gregor Mendel in the nineteenth century was an uncomfortable fit with evolution, as many scientists saw it. They weren't at all certain that natural populations contained enough genetic variation for natural selection to create new species. So they entertained other explanations, including inheritance of acquired characteristics, "directed" variation toward a goal, or sudden large mutations that resulted in new species.

In the field of paleontology, the scientist who did most to resolve these questions was George Gaylord Simpson, who was on the staff of the American Museum of Natural History for 30 years.At a time when other paleontologists were convinced that the fossil record could best be explained by directed variation, Simpson disagreed. He said that fossil patterns needed no mystical or goal-oriented processes to explain them. For example, where others saw the modern horse as having arisen in a single advance toward the specialized form, Simpson saw the path as that of an irregular tree that had many side-branches leading off to extinction.

Simpson argued that the evolution of mammals, as seen in their fossilized remains, fit perfectly well with the new mechanisms of population genetics being studied at the time. He used the then-new mathematical methods to clarify how evolution occurred in "gene pools" in populations, not in individual members of the population.

Importantly, he showed that gaps in the fossil record reflected periods of substantial change through rapid "quantum evolution" in small populations, leaving little fossil evidence behind. At other times, he observed, rates of change could be so slow as to seem almost nonexistent.

Read more about Simpson HERE.

Eocursor parvus from South Africa

A primitive ornithiscian dinosaur from the Late Triassic of South Africa, and the early evolution and diversification of Ornithischia. 2007. R. Butler et al. Proc. of the Royal Society B 274.



From The Times On-line:

Eocursor is among the earlier members of the Ornithischia, and the most complete ornithischian skeleton yet found from the Triassic period, between 250 million and 200 million years ago.

“The few ornithischian fossils from the Triassic are incomplete and controversial, so we know virtually nothing about the group’s early evolution. Eocursor is enormously important because it helps to fill this gap in the fossil record.”



The miniature dinosaur fossil was discovered in 1993 in Orange Free State (now Free State), South Africa, but the specimen has only recently been studied exhaustively by scientists. It has been identified as a new species from details of its skull, backbone, arms, pelvis and legs.

Taphonomy of a Black Bear

As a palaeontologist with an interest in taphonomy I was very pleased when the CMNH’s Invertebrate Zoologist, Dr. Joe Keiper, announced that he was going to place the carcass of a black bear on one of the parcels of land owned by the museum and watch it decay. The carcass has been frozen for about a decade. Almost every day Joe is posting a photo and information on the decay process.

Joe does a lot of forensic entomology for the local and state law enforcement agencies, and he’s primarily interested in the succession of bugs that utilize the carcass. The data that he gathers will also help fill in the big data gaps we have on just how big animals decompose (and maybe someday enter the fossil record).

Go check out the Bugs and Bear Blog.

Gigantoraptor erlianensis from China

A gigantic bird-like dinosaur from the Late Cretaceous of China. 2007. Xing Xu, et al. Nature 447: 844-847.


Zhao Chuang and Xing Lida/IVPP

From David Cyranoski at News@Nature.com:

The newly discovered oviraptorid Gigantoraptor erlianensis is thought to have been 8 m long, 3.5 m high at the hip and 1,400 kg in weight — 35 times as heavy as its next largest family members and 300 times the size of smaller ones such as Caudiperyx.

Comparison of the animal with other known dinosaurs — looking at more than a hundred characteristics, including limb proportions — puts Gigantoraptor firmly in the Oviraptoridae family

Gigantoraptor had long arms, bird-like legs, a toothless jaw, and probably a beak. There are no clear signs as to whether it was feathered. However, judging from its close affinity to other dinosaurs known to have been feathered, Xing Xu of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing speculates that it was.

The animal was found by accident in April 2005, when Xu was re-enacting the find of a sauropod for a Japanese documentary film crew. While the cameras were rolling, Xu randomly picked out a bone from a dig site in the Gobi Desert, where a unique sauropod had previously been found. As he started clearing away the dirt, Xu soon realized that the bone was not from a sauropod. Its large size suggested a tyrannosaur, but he couldn't be sure. "I told them to stop filming," recalls Xu. "I said, 'This is not for your programme.'"



Abstract: An evolutionary trend of decreasing size is present along the line to birds in coelurosaurian theropod evolution, but size increases are seen in many coelurosaurian subgroups, in which large forms are less bird-like. Here we report on a new non-avian dinosaur, Gigantoraptor erlianensis, gen. et sp. nov., from the Late Cretaceous Iren Dabasu Formation of Nei Mongol, China.

Although it has a body mass of about 1,400 kg, a phylogenetic analysis positions this new taxon within the Oviraptorosauria, a group of small, feathered theropods rarely exceeding 40 kg in body mass. A histological analysis suggests that Gigantoraptor gained this size by a growth rate considerably faster than large North American tyrannosaurs such as Albertosaurus and Gorgosaurus.

Gigantoraptor possesses several salient features previously unknown in any other dinosaur and its hind limb bone scaling and proportions are significantly different from those of other coelurosaurs, thus increasing the morphological diversity among dinosaurs. Most significantly, the gigantic Gigantoraptor shows many bird-like features absent in its smaller oviraptorosaurian relatives, unlike the evolutionary trend seen in many other coelurosaurian subgroups

Dinosaurs Alive! In Edmonton

The Edmonton ‘Telus World of Science’ (aka the Space Sciences Center when I lived there many moons ago) has a summer long celebration of Dinosaurs with activities for the whole family. In addition to the exhibits and the IMAX film “Dinosaurs Alive!”, there will be a series of special lectures and events, such as:

June 16, 2pm: Dr. Philip Currie talks on “Hunting Dinosaurs in the Gobi Desert”

June 16&17: “Brick Master” Robin Sather builds an Albertaceratops out of Lego(!)

June 23, 2pm: I talk about Albertan ceratopsians & bone beds

Ancient DNA Traces Woolly Mammoth's Disappearance

image

From the press release:

DNA lifted from the bones, teeth, and tusks of the extinct mammoths revealed a “genetic signature” of a range expansion after the last interglacial period. After the mammoths’ migration, the population apparently leveled off, and one of two lineages died out.

“In combination with the results on other species, a picture is emerging of extinction not as a sudden event at the end of the last ice age, but as a piecemeal process over tens of thousands of years involving progressive loss of genetic diversity,” said Dr. Ian Barnes.

“For the mammoth, this seems much more likely to have been driven by environmental rather than human causes, even if humans might have been responsible for killing off the small, terminal populations that were left.”

Barnes had earlier found evidence that bison, bears, and lions underwent major population shifts twenty-five to fifty thousand years ago. Those results came as a surprise, the researchers said, because scientists tended to think that the major environmental changes happened about fifteen to twenty-five thousand years ago, when the glaciers reached their fullest extent. The findings also offered early human hunters a potential alibi; they didn’t come on the scene in large numbers until even later.

Their genetic data indicate that Siberian mammoths expanded from a small base some time before sixty thousand years ago. Moreover, they found two distinct genetic groups, implying that mammoths had diverged in isolation for some time before merging back into a single population. The DNA further suggests that no later than forty thousand years ago, one of the groups died out, leaving only the second alive at the time of the mammoth’s last gasp.

DPP Workshop

As promised here are a few photos from the recent workshop in Dinosaur Provincial Park organized by Dr. Don Brinkman of the Royal Tyrrell Museum, and attended by almost all of the vertebrate palaeontologists and grad students working in Alberta. It was designed to give the MANY new palaeo students in the province a chance to see one of the most important dinosaur localities in the world. They had a full week of hiking all over the Park, excavating material they discovered, and taking in over two dozen talks given by just about everyone in attendance.

Group (almost everyone) Photo © Philip Currie 2007

A Discovery Channel.Ca crew shot a segment on me for The Daily Planet for broadcast next Fall.

Butterflies in DPP

Don Henderson

Eric Snively

Part of the crew in the Steveville badlands of DPP.

The U of A excavating a Basilemys in Steveville.

Plastering the turtle.

U of A Ph.D. Student, Phil Bell and his fiance, Park Interpreter Marcia.

Don Brinkman fiddles in The Valley of the Moon, DPP, during the closing ceremonies.

T.rex Didn't Turn On A Dime

A 3D interactive method for estimating body segmental parameters in animals: Application to the turning and running performance of Tyrannosaurus rex. 2007. John R. Hutchinson, et al. J. of Theoretical Biology 246: 660-680.

Scientists have used detailed computer models to work out the weight of a typical "king of the dinosaurs", and determined how it ran and turned.

From the BBC:

The results indicate a 6 to 8-tonne T. rex was unlikely to have topped 40km/h (25mph) and would take a couple of seconds to swivel 45 degrees.

The team's computer modelling system estimated the centre of mass position and the inertia (resistance to turning), which have ramifications for how T. rex would have stood and moved and what it would have looked like.

"We've shown there's no way it could weigh 3-4 tonnes as some people have suggested. It had to have weighed 6-8 tonnes,"

The study indicates the animal would have changed direction incredibly slowly because of its massive inertia, taking more than two seconds to make a quarter-turn. The species certainly could not have pirouetted rapidly on one leg, as popular illustrations have sometimes pictured it, and other large dinosaurs, doing.

More agile prey would have given the slip to a marauding T. rex quite easily, it seems.

"These were big clunky things - T. rex and the animals it probably preyed on. We have to slow down our view of that ecosystem," said Dr Hutchinson, who is currently lecturing in biomechanics at the Royal Veterinary College in the UK.

It’s raining here in Dinosaur Park so we’re back in the Field Station for an afternoon of talks from some of the assembled palaeo-brain trust. So, here’s a quick update. I’ll try to post some photos from the workshop later in the week.

Another Sunday Funny

...thanks to Frank Cho.

James Watson's Genome Sequenced

From News@Nature.com:

Scientists in Houston presented Watson with a DVD of his genome sequence, which they said was the "first individual genome to be sequenced for less than $1 million". The carefully worded claim may be an acknowledgement that another personal genome project has already been completed: J. Craig Venter has deposited his genome sequence into the public GenBank database, he told Nature two weeks ago.

image

The only deliberate omission from Watson's sequence is that of a gene linked to Alzheimer's disease, which Watson, who is now 79, asked not to know about because it is incurable and claimed one of his grandmothers.

Scientists said yesterday that Watson's genes showed some predisposition to cancer. Watson — who, working with Francis Crick, deduced DNA's structure in 1953 — has had skin cancer, and a sister had breast cancer.

Orangutans as a Model for Bipedalism

Origin of Human Bipedalism As an Adaptation for Locomotion on Flexible Branches. 2007. S. K. S. Thorpe, et al. Science 316: 1328 – 1331.

By observing wild orangutans, a research team has found that walking on two legs may have arisen in relatively ancient, tree-dwelling apes, rather than in more recent human ancestors that had already descended to the savannah, as current theory suggests.

From the press release:

Upright walking, or bipedalism, has long been considered a defining feature of humans and our closest ancestors. One of the most popular explanations, known as the savannah hypothesis, suggests that the ancestors to chimps, gorillas and humans descended from the trees and began walking on the ground on all fours.

Over time, this four-legged gait would have evolved into the "knuckle-walking" that chimps and gorillas still use today and then into upright, two-legged walking in humans.

Paleontologists have conventionally used signs of bipedalism as key criteria for distinguishing early human, or "hominin," fossils from those of other apes. But, this distinction is complicated by recent fossil evidence that some early hominins, including Lucy (Australopithecus afarensis), lived in woodland environments, while even earlier forms such as Millennium Man (Orrorin) appear to have lived in the forest canopy and moved on two legs.

Because these ancestors were probably fruit-eaters, as orangutans are, they would have needed a way to navigate the thin, flexible branches at the tree's periphery, where the fruit typically is. Moving on two legs and using their arms primarily for balance, or "hand-assisted bipedalism," may have helped them travel on these branches.

Crompton and his colleagues came to their conclusions by observing wild orangutans in Sumatra, Indonesia. Orangutans spend almost their whole lives in trees, making them useful models for how our ancestors moved around several million years ago.

"Our findings blur the picture even further," said Crompton. "If we're right, it means you can't rely on bipedalism to tell whether you're looking at a human or other ape ancestor. It's been getting more and more difficult for us to say what's a human and what's an ape, and our work makes that much more the case."

Watch a movie of a possible scenario for great ape locomotor diversification.