Tuesday, September 29, 2009

A Sick T. rex

Common Avian Infection Plagued the Tyrant Dinosaurs. 2009. E.D.S. Wolff, et al. PLoS One PLoS ONE 4(9): e7288.

A new study pins the demise of ‘Sue’ and other tyrannosaurs with similar scars on an avian parasitic infection called trichomonosis, caused by a single-celled parasite that causes similar pathologies on the mandibles of modern birds, raptors in particular.

The focus of the new study was a survey of lesions on the jaws of Sue and nine other tyrannosaur specimens. The lesions had previously been attributed to bite wounds or, possibly, a bacterial infection.

It is possible the infection in her throat and mouth may have been so acute that the 42-foot-long, 7-ton dinosaur starved to death, says Wolff.

The scars of combat among tyrannosaurs and other dinosaurs, Wolff notes, are not uncommon, but differ notably from the lesions that are the focus of the current study. The holes caused by trichomonosis tend to be neat and have relatively smooth edges, while bite marks are often messy, and they scar and puncture bone in ways that are not readily comparable.

"The lesions we observe on Sue suggest a very advanced stage of the disease and may even have been the cause of her demise," says Wolff. "It is a distinct possibility as it would have made feeding incredibly difficult. You have to have a viable pharynx. Without that, you won't make it for very long, no matter how powerful you are." link

Monday, September 28, 2009

McAbee Eocene Fossil Beds Lose Protection

“The B.C. Paleontological Association has pulled out of an agreement signed last year with government to protect a renowned fossil bed near Cache Creek, B.C..

An official with the B.C. government also acknowledged there is no money for oversight at McAbee fossil beds. Monitoring of the site was one of the goals contained in the agreement designed to protect what one researcher called a world-class site now used as a tourist destination.

A memorandum of understanding (MOU) was signed last year with the province, B.C. Paleontological Association, Royal B.C. Museum and Thompson Rivers University.
Its goals included mapping and potentially expanding the fossil beds from the Eocene era, 50 to 60 million years ago, as well as monitoring finds and collecting and storing significant fossils at TRU.

“Because government pulled its funding the B.C. Paleontological Alliance has withdrawn from the MOU,” said TRU geology professor Ken Klein.

“Government didn’t do anything it said it would do. It’s unfortunate. There’s no money for anything.”

From the Kamloops Daily News.

Sunday, September 27, 2009

Raid of The Dinosaurs!

Another great, goofy sci-fi dinosaur story for a Sunday afternoon from the early days of DC Comics care of Atomic Surgery.

Evolution of Weaponry in Female Bovids

Evolution of weaponry in female bovids. 2009. T. Stankowich and T. Caro. PRSB, Published online before print September 16, 2009.

Abstract: Weaponry is ubiquitous in male ungulates and is driven by intrasexual selection, but the mystery surrounding its sporadic presence in females remains unsolved. Female horns are often smaller and shaped differently to male horns, suggesting a different function; indeed, hypotheses explaining the presence of female horns include competition for food, male mollification and defence against predators.

Here we use comparative phylogenetic analyses to show that females are significantly more likely to bear horns in bovids that are conspicuous due to large body size and living in open habitats than inconspicuous species living in closed habitats or that are small. An inability to rely on crypsis or take refuge in deep vegetation has apparently driven the evolution of horns for defence against predators in female bovids, a finding supported by many field observations.

Typically, exceptions are small species where females are territorial (e.g. duikers) and use horns in intrasexual contests. Furthermore, we suggest that conspicuousness and territoriality hypotheses may explain other instances of female cranial weaponry (i.e. antlers and ossicones) in other horned ruminants.

Our phylogenetic reconstruction indicates that the primary function of horns in females is linked to antipredator defence in most clades, but occasionally to intrasexual competition in others.

More work on modern animals that can be used when considering the evolution of horned dinosaur ornamentation.

Click to enlarge

Sunday Funnies

Today's reprint of Liberty Meadows by Frank Cho.

When Whales Walked Into The Water

Relationships of Cetacea (Artiodactyla) Among Mammals: Increased Taxon Sampling Alters Interpretations of Key Fossils and Character Evolution. 2009. M. Spaulding, et al. PLoS ONE 4(9): e7062.

Painting by the great Carl Buell
A new study shows that cetacean (whale) ancestors probably moved into water before changing their diet (and their teeth) to include carnivory; Indohyus, a 48-million year-old semi-aquatic herbivore, and hippos fall closest to cetaceans when the evolutionary relationships of the larger group are reconstructed.

"Indohyus is interesting because this fossil combines an herbivore's dentition with adaptations such as ear bones that are adapted for hearing under water and are traditionally associated with whales only."

The origin of whales, dolphins, and porpoises—with their highly modified legs and lack of hair—has long been a quandary for mammalogists. Recent genetic research has found that among artiodactyls, hippos are the cetaceans' closest living relatives.

Traditionally, the origin of whales was linked to the mesonychids, an extinct group of carnivores that had singly-hoofed toes. The recent discovery of Indohyus, a clearly water-adapted herbivore, complicates this picture (as new fossils often do) because of ear bones similar to those of modern cetaceans, which are theorized to help the animal have heard better while under the water.

To tease apart different potential evolutionary histories over 80 living and fossil taxa scored for 661 morphological and behavioral characters (such as presence of hair or the shape of and ankle bone). Forty-nine new DNA sequences from five nuclear genes were also added to the mix of more than 47,000 characters.

The team found that the least complex evolutionary tree places Indohyus and similar fossils close to whales, while mesonychids are more distantly related. Hippos remain the closest living relatives.

These results suggest that cetacean ancestors transitioned to water before becoming carnivorous but that the meat-eating diet developed while these ancestors could still walk on land. link

Saturday, September 26, 2009

Born This Day: Winsor McCay

Sept. 26, 1987 – July 26, 1934
McCay was one of the great American artists of the last century. He is best known for his newspaper comic strip Little Nemo in Slumberland that ran from 1905 to 1914, and the animated cartoon creation Gertie the Dinosaur (1914). For this cartoon McCay hand drew each frame of film. He took it on a tour of the vaudeville circuit and delighted audiences by being able to ‘interact’ with Gertie. Gertie is considered by many as the first true animated character to be featured in a film.

"Much of what he achieved was simply lost: like a rocket exploding brilliantly in the midnight sky, his work illuminated the medium for a breathtaking instant and then faded into virtual oblivion as, one by one, the scintillating spangles of his achievements winked out, leaving his colleagues as much in the dark as before. He was so far ahead of his time that many of his innovations were beyond the abilities of his contemporaries: what he had discovered and demonstrated about the capacities of each medium had to be re-discovered decades later by the next generation of cartoonists."by R.C Harvey

Happy Birthday to Victoria Vetri

Victoria turns 65 today. She had a career doing bit parts in 1960’s TV including Batman and Star Trek (Isis the cat), before becoming playmate of the year (1968) for Playboy magazine. This lead to her starring role in When Dinosaurs Ruled the Earth.

She also had a small role in Rosemary’s Baby under her stage name of Andrea Dorian taken from the ill-fated ship, Andrea Doria.

First Evolutionary Branching for Bilateral Animals

Assessing the root of bilaterian animals with scalable phylogenomic methods. 2009. A. Hejnol, et al. Proc. Royal Soc. B. Published online before print September 16, 2009.

Kamandi © DC Comics
Researchers have determined that the flatworm group Acoelomorpha is a product of the deepest split within the bilateral creatures — multicelled organisms that, like humans, have symmetrical body forms.

The worm is “as distant as an animal can be in bilateria and still be a bilaterian,” said Dunn.

Friday, September 25, 2009

Anchiornis huxleyi: New Feathered Theropod Older than Archaeopteryx

Now this is news!

A pre-Archaeopteryx troodondid theropod from China with long feathers on its metatarsus. 2009. Dongyu Hu, et al. Nature 461: 640-643. [DOI is not active yet, so check out Nature]

Anchiornis huxleyi
Abstract: The early evolution of the major groups of derived non-avialan theropods is still not well understood, mainly because of their poor fossil record in the Jurassic. A well-known result of this problem is the ‘temporal paradox’ argument that is sometimes made against the theropod hypothesis of avian origins. Here we report on an exceptionally well-preserved small theropod specimen collected from the earliest Late Jurassic Tiaojishan Formation of western Liaoning, China.

The specimen is referable to the Troodontidae, which are among the theropods most closely related to birds. This new find refutes the ‘temporal paradox’ and provides significant information on the temporal framework of theropod divergence.

Furthermore, the extensive feathering of this specimen, particularly the attachment of long pennaceous feathers to the pes, sheds new light on the early evolution of feathers and demonstrates the complex distribution of skeletal and integumentary features close to the dinosaur–bird transition.

Read the story at The New Scientist

click to enlarge

They Might Be Giants: Science Is Real

A few weeks ago I linked to this video by They Might Be Giants. Their new cd,& DVD of kid-friendly songs about science, Here Comes Science, is out now. link

Thursday, September 24, 2009

Born This Day (1922): Bert I. Gordon

Gordon was a movie producer of low, low budget films known for having great posters that sold the film. These films were fodder for many episodes of Mystery Science Theater 3000. He takes a bow here for “King Dinosaur”

New Starting Date For Quaternary

Doom Patrol © DC Comics
Controversy over when exactly the Quaternary Period began has raged for decades, with attempts in 1948 and 1983 to define the era. In 1983 the boundary was fixed at 1.8 million years, a decision which sparked argument within the earth science community as this point was not a 'natural boundary' and had no particular geological significance.

For practical reasons such boundaries should ideally be made as easy as possible to identify all around the world. The new boundary of 2.6 million years is just that," concluded Gibbard, "hence we are delighted at finally achieving our goal of removing the boundary to this earlier point."

The decision has been made by the International Commission on Stratigraphy (ICS), the authority for geological science which has acted to end decades of controversy by formally declaring when the Quaternary Period, which covers both the ice age and moment early man first started to use tools, began.

"It has long been agreed that the boundary of the Quaternary Period should be placed at the first sign of global climate cooling," said Professor Philip Gibbard. "What we have achieved is the definition of the boundary of the Quaternary to an internationally recognised and fixed point that represents a natural event, the beginning of the ice ages on a global scale." link

Kong By Powers

I missed this posting over at Atomic Surgery about the legendary SF artist Richard Powers illustrating King Kong.

Died This Say: William Diller Matthew

Feb. 19, 1871 – Sept. 24, 1930

Matthew was a superb mammalian paleontologist and important biogeographic theorist, and also G. G. Simpson's primary mentor. Matthew published voluminiously on the fossil record of mammals and advocated a fully modern approach to taxonomy that emphasized tying scientific names to natural biological populations. His 1930 paper gives a clear statement of this position.

Matthew's key biogeographic theory was that waves of faunal migration repeatedly went from the northern continents southwards. This theory, which had obvious racial and political overtones, was justified by a "stabilist" view of paleogeography (i.e., that the continents had never moved from their modern positions), and by evidence from the relatively young fossil record of mammals, at the expense of other data that would have shown the more ancient interconnections among South America, Africa, India, and Australia. Remarkably, Matthew remained a Darwinian despite working for the autocratic orthogeneticist H. F. Osborn for three decades.

Info from HERE. Image from HERE.

Saturday, September 19, 2009

Frenchman Formation Terrestrial Ecosystem Conference Abstracts Now Available

For those of you who missed the conference, The Royal Saskatchewan Museum Contributions to Science No. 12, Frenchman Formation Terrestrial Ecosystem Conference, Program and Abstracts is now available by contacting the RSM Associates at rsm.associates@gov.sk.ca.

This sells for $15.95 Cdn (shipping and taxes extra).

Other great publications on Saskatchewan vertebrate paleontology are available here.

Thursday, September 17, 2009

Raptorex: Little Big Rex

Tyrannosaurid Skeletal Design First Evolved at Small Body Size. P.C.Sereno, et al., early online edition of Science, Sept. 17, 2009.

Drawing by Todd Marshall
A 9-foot dinosaur from northeastern China had evolved all the hallmark anatomical features of Tyrannosaurus rex at least 125 million years ago.
Raptorex displays all the hallmarks of its famous descendant, Tyrannosaurus rex, including a large head compared to its torso, tiny arms and lanky feet well-suited for running. The Raptorex brain cast also displayed enlarged olfactory bulbs—as in T. rex—indicating a highly developed sense of smell.

"It's really stolen from tyrannosaurids all the fire of the group," Sereno said. All that Raptorex left for its descendants is "a suite of detailed features largely related to getting bigger."

Sereno marvels at the scalability of the tyrannosaur body type, which when sized up 90 million years ago completely dominated the predatory eco-niche in both Asia and North America until the great extinction 65 million years ago at the end of the Cretaceous Period.

"On other continents like Africa, you have as many as three large predators living in the same areas that split among them the job of eating meat," he said. But in Africa, the allosaurs never went extinct, as they did in North America, possibly presenting an evolutionary opportunity for Raptorex. "We have no evidence that it was a competitive takeover," said Sereno, "because we have never found large tyrannosaurs and allosaurs together."

Henry Kriegstein, a private fossil collector, brought the nearly complete Raptorex skeleton to Sereno's attention after buying it from a vendor. After Sereno and colleagues finish a more detailed study of Raptorex, it will be returned to a museum in Inner Mongolia, the place where the fossil was illicitly excavated. link

Tuesday, September 15, 2009

The Evolution of The First Fowers

Seed fertilization, development, and germination in Hydatellaceae (Nymphaeales): Implications for endosperm evolution in early angiosperms. 2009. P.J.Rudall, et al. American Journal of Botany, First published online August 13, 2009.

How did flowering plants evolved from the nonflowering gymnosperms?
New work on Trithuria, a genus in the plant family Hydatellaceae, thought to be one of the earliest families of angiosperms, suggests that double fertilization occurs. Double fertilization is a unique feature of flowering plants where one sperm nucleus unites with the egg, producing the embryo, while another sperm nucleus unites with a separate nucleus from the female, producing the endosperm. The endosperm is divided into two regions—the micropylar and chalazal regions.

In Trithuria, the cells of the micropylar region divide many times to form the multi-celled endosperm. However, the chalazal region forms a single-celled haustorium, a structure that absorbs nutrients and ultimately degenerates to form an empty space in the seed. This situation is broadly similar to that of some waterlilies and some monocots but differs from that of many other early-diverging angiosperms such as Amborella, in which the endosperm is formed from the chalazal region.

One of the current hypotheses is that the endosperm originated as a monstrous proembryo that fails to develop into a plant. Rudall and colleagues' observations support this theory.

Anatomical Record Dino Articles Now Available For Free Download

All of the articles from The Anatomical Record (Volume 292 Issue 9 (Sept. 2009) Special Issue: Unearthing the Anatomy of Dinosaurs: New Insights Into Their Functional Morphology and Paleobiology, edited by Peter Dodson) listed here are available from the publisher for free download HERE.

Many thanks to the publisher and editor for putting this issue togather and for making these articles available!

Saturday, September 12, 2009

Samson Up For Auction

Unfortunate news: “Samson”, the T. rex goes for auction in Vegas on Oct. 3, 2009. The sad details are here.

When I came back from the gobi the glossy brochure for the auction was in my in-box. It features an article by Peter Larson on the specimen. The auction also features an Edmontosaurus from Black Hills and a composite Einiosaurus from Canada Fossils.

Friday, September 11, 2009

Anatomical Record: Special Issue on Dinosaurs

The latest issue of The Anatomical Record is a special issue edited by Peter Dodson. I've listed all the papers in the volume and hot linked the titles back to those papers if you want to order a copy. And, I'm making an request to all the authors that read this blog to please send me pdfs of your papers. Thanks!

Volume 292 Issue 9 (September 2009)
Unearthing the Anatomy of Dinosaurs: New Insights Into Their Functional Morphology and Paleobiology; Peter Dodson, Jeffrey T. Laitman. Published Online: Aug 26 2009 4:01PM


Dinosaurs and Their Relatives are Alive and Well in The Anatomical Record (p 1235-1236). Jeffrey T. Laitman, Kurt H. Albertine. Published Online: Aug 26 2009 4:01PM

The Real Jurassic Park: Joseph Leidy's Heirs Reconstruct the Anatomy of Dinosaurs (p 1237-1239). Jeffrey T. Laitman. Published Online: Aug 26 2009 4:01PM

Dinosaurs in the Year of Darwin (p 1240-1245). Peter Dodson. Published Online: Aug 26 2009 4:01PM

Cranial Anatomy

New Insights Into Dinosaur Jaw Muscle Anatomy (p 1246-1265). Casey M. Holliday. Published Online: Aug 26 2009 4:01PM

New Insights Into the Brain, Braincase, and Ear Region of Tyrannosaurs (Dinosauria, Theropoda), with Implications for Sensory Organization and Behavior (p 1266-1296). Lawrence M. Witmer, Ryan C. Ridgely. Published Online: Aug 26 2009 4:01PM

A Functional Explanation for Denticulation in Theropod Dinosaur Teeth (p 1297-1314). Domenic C. D'Amore. Published Online: Aug 26 2009 4:01PM

Endocranial Anatomy of Lambeosaurine Hadrosaurids (Dinosauria: Ornithischia): A Sensorineural Perspective on Cranial Crest Function (p 1315-1337). David C. Evans, Ryan Ridgely, Lawrence M. Witmer. Published Online: Aug 26 2009 4:01PM

A Comparison of the Jaw Mechanics in Hadrosaurid and Ceratopsid Dinosaurs Using Finite Element Analysis (p 1338-1351)
Phil R. Bell, Eric Snively, Lara Shychoski. Published Online: Aug 26 2009 4:01PM

Jaw Mechanics in Basal Ceratopsia (Ornithischia, Dinosauria) (p 1352-1369). Kyo Tanoue, Barbara S. Grandstaff, Hai-Lu You, Peter Dodson. Published Online: Aug 26 2009 4:01PM

The Facial Integument of Centrosaurine Ceratopsids: Morphological and Histological Correlates of Novel Skin Structures (p 1370-1396). Tobin L. Hieronymus, Lawrence M. Witmer, Darren H. Tanke, Philip J. Currie. Published Online: Aug 26 2009 4:01PM

Postcranial Anatomy

Biomechanics of Dromaeosaurid Dinosaur Claws: Application of X-Ray Microtomography, Nanoindentation, and Finite Element Analysis (p 1397-1405). Phillip L. Manning, et al. Published Online: Aug 26 2009 4:01PM

Femoral Strength and Posture in Terrestrial Birds and Non-Avian Theropods (p 1406-1411). Andrew A. Farke, Justy Alicea. Published Online: Aug 26 2009 4:01PM

Finite Element Analyses of Ankylosaurid Dinosaur Tail Club Impacts (p 1412-1426). Victoria M. Arbour, Eric Snively. Published Online: Aug 26 2009 4:01PM

Influence of Sequence Heterochrony on Hadrosaurid Dinosaur Postcranial Development (p 1427-1441). Merrilee F. Guenther. Published Online: Aug 26 2009 4:01PM

Variation in Center of Mass Estimates for Extant Sauropsids and its Importance for Reconstructing Inertial Properties of Extinct Archosaurs (p 1442-1461). Vivian Allen, Heather Paxton, John R. Hutchinson. Published Online: Aug 26 2009 4:01PM


Palaeobiological Implications of the Bone Histology of Pterodaustro guinazui (p 1462-1477). Anusuya Chinsamy, Laura Codorni├║, Luis Chiappe. Published Online: Aug 26 2009 4:01PM

Pathologic Bone Tissues in a Turkey Vulture and a Nonavian Dinosaur: Implications for Interpreting Endosteal Bone and Radial Fibrolamellar Bone in Fossil Dinosaurs (p 1478-1484). Anusuya Chinsamy, Allison Tumarkin-Deratzian. Published Online: Aug 26 2009 4:01PM

Evaluation of Long Bone Surface Textures as Ontogenetic Indicators in Centrosaurine Ceratopsids (p 1485-1500). Allison R. Tumarkin-Deratzian. Published Online: Aug 26 2009 4:01PM

Evolution of the Respiratory System in Nonavian Theropods: Evidence From Rib and Vertebral Morphology (p 1501-1513)
Emma R. Schachner, Tyler R. Lyson, Peter Dodson. Published Online: Aug 26 2009 4:01PM

A Life Table for Psittacosaurus lujiatunensis: Initial Insights Into Ornithischian Dinosaur Population Biology (p 1514-1521). Gregory M. Erickson, Peter J. Makovicky, Brian D. Inouye, Chang-Fu Zhou, Ke-Qin Gao. Published Online: Aug 26 2009 4:01PM

Debuted This Day (1966): It’s About Time

It's About Time ran only one season on CBS, from September 11, 1966 until August 27, 1967; the sitcom starred Jack Mullaney and Frank Aletter as two 1960's astronauts who break the time barrier and end up in prehistoric times.

The astronauts are forced to take up with primitive (and dumb) cave dwellers played by the great Joe E. Ross as Gronk - with another comedy legend, Imogene Coca (Your Show of Shows) seen as his nagging wife Shadd.

Mid-season the premise was flipped as the cave people and astronauts returned in the space craft to 1967. The focus of the show shifted to stars Coca and Ross as they reacted to the unfamiliar surroundings, setting up home in 20th-century New York City.

Watch the original promo. Watch for the stop-motion dinos.

Thanks to TV Party for this info!

O2 Elevation Lead To Rise of Life

Fluctuations in Precambrian atmospheric oxygenation recorded by chromium isotopes. 2009. R. Frei, et al. Nature 461: 250-253.

Analysis of a rock type found only in the world's oldest oceans has shed new light on how large animals first got a foothold on the Earth. A scientific team have for the first time managed to plot the rise and fall of oxygen levels in the Earth's atmosphere over the last 3.8 billion years.

By analysing the isotopes of chromium in iron-rich sediments formed in the ancient oceans, the team has found that a rise in atmospheric oxygen levels 580 million years ago was closely followed by the evolution of animal life.

"Our research confirms for the first time that a rise in atmospheric oxygen was the driving force for oxygenation of the oceans 580 million years ago, and that this was the catalyst for the evolution of large complex animals."

"But instead of this rise being steady and gradual over time, what we saw in our data was a very unstable situation with short-lived episodes of free oxygen in the atmosphere early in Earth's history, followed by plummeting levels around 2 billion years ago.

"It was not until a second rise in atmospheric oxygen 580 million years ago that larger complex animals were able to get a foothold on the Earth." link

Thursday, September 10, 2009

Self-Amputation Saves A Leg

Flip, flop and fly: modulated motor control and highly variable movement patterns of autotomized gecko tails. 2009. T. E. Higham and A.P. Russell. Biology Letters, Published online before print September 9, 2009.
Evolutionary biologists Timothy Higham of Clemson and Anthony Russell (my Ph.D. advisor) of Calgary have found that the self-severed tail of some geckos shows a complex pattern of repeating movements to distract the attacker.

"Autotomy is the process by which an appendage is voluntarily shed by animal. A number of reptiles, amphibians, mammals and many invertebrates developed the defense mechanism over time," said Higham. "Some geckos' severed tails can move repeatedly, allowing the gecko to escape and grow a replacement. It's like a gecko's personal injury insurance policy."

Higham and Russell explored how the tail continues to function, using motion to entice a predator while the gecko escapes.

The research shows that a severed – autotomized – tail of leopard gecko makes four to eight rhythmic moves per second with one or two complex movements – dramatic flips or lunges – during the first 50 seconds of its separation.

How does the tail do it? The scientists theorize that central pattern generators in the tail control the actions. Central pattern generators are made up of a network of nerve cells that enable repeatable pattern of behavior, such as chewing, walking, flying.

The gecko study adds to the evidence that central pattern generator networks can function without being linked to a brain or central nervous system. The findings present the prospect that human central pattern generators could play a role in restoring motion to people with spinal injuries. link

Born This Day: Stephen Jay Gould

Sept. 10, 1941 - May 20. 2002
Here’s a nice piece on Gould by Henry Lowood from the Stanford Presidential Lectures in the Humanities and Arts.

Wednesday, September 09, 2009

Born This Day: Joseph Leidy

Sept. 9, 1823 - April 30, 1891

From The Academy of Natural Sciences:

Leidy is known as the "Father of American Vertebrate Paleontology". He described the first relatively complete dinosaur skeleton, Hadrosaurus, and introduced many American and European scientists to the fossil riches of the American West. Leidy's consummate skill in comparative anatomy would allow him to identify and characterize even the most fragmentary fossil material.

Leidy was also the "Founder of American Parasitology," a Professor of Anatomy at the University of Pennsylvania, a pioneering protozoologists, an influential teacher of Natural History, an accomplished microscopist and scientific illustrator, and an expert on a variety of subjects encompasing the earth and natural sciences. He published scientific papers on more than a thousand extinct and living protozoa, fungi and invertebrates and vertebrates as well as an assortment of publications on human biology and medicine. He was also one of the earliest supporters of Charles Darwin.

Sunday, September 06, 2009

Evolution of the 4-Chambered Heart

Reptilian heart development and the molecular basis of cardiac chamber evolution. 2009. K. Koshiba-Takeuch, et al. Nature 461: 95-98.

The cold-blooded reptilian heart in action.
Young Romance #1 (1947) by Simon & Kirby
Scientists have traced the evolution of the four-chambered human heart to a common genetic factor linked to the development of hearts in turtles and other reptiles.
"This is the first genetic link to the evolution of two, rather than one, pumping chamber in the heart, which is a key event in the evolution of becoming warm-blooded," said Benoit Bruneau. "The gene involved, Tbx5, is also implicated in human congenital heart disease, so our results also bring insight into human disease."

With four chambers—two atria and two ventricles—humans and all other mammals have completely separate blood flows to the lungs and to the rest of the body, which is essential for us to be warm-blooded. The different reptiles offer a sort of continuum from three to four chambers.

To better understand reptile heart evolution, the scientists examined the transcription factor Tbx5. Mutations in the human gene that encodes Tbx5 result in congenital heart disease and, in particular, defects in the ventricular septum, the muscular wall that separates the ventricle into two sections. Levels of Tbx5 is a key player in the evolution of septum development between the left and right ventricles.

The team looked at Tbx5 distribution in the turtle and the green anole lizard. During the early stages of heart formation in both reptiles, Tbx5 activity is found throughout the embryonic ventricular chamber. In the lizard, which forms only one ventricle, this pattern stays the same as the heart develops. However, in the turtle, which has a primitive septum that partially separates the ventricles into left and right sides, distribution of Tbx5 is later gradually restricted to the area of the left ventricle, resulting in a left-right gradient of Tbx5 activity. This meant that the gradient of Tbx5 forms later and less sharply in the turtle than in species with a clear septum, such as mammals, providing a tantalizing clue about how septation evolved.

Further evidence from mice conclusively showed that a sharp line delineating an area of high level of Tbx5 is critical to induce formation of a septum between the two ventricles. link

Saturday, September 05, 2009

Born This Day: Raquel Welch

The cinema's best known cave woman!

Friday, September 04, 2009

A Fond Farewell To Steve Green

Just after I got out of the gobi here in Mongolia I got the sad news from Cleveland that one of my department's long time volunteers, and good friend, Steve Green, had passed away after a valiant fight against cancer.

Steve was one of the first persons I meet when I arrived in Cleveland 5 years ago, and he quickly became a valued member of the the VP crew. He did a great job prepping fossils, entering data, and trying to keep our old computers going. In addition to working in my Dept. he had also volunteered in Cultural Anthropology and worked part-time with security.

This is the only picture of Steve I've got on my computer but I'm sure that he'd be happy to be remembered prepping fossils.

Evolution of Enamel Loss

Molecular Decay of the Tooth Gene Enamelin (ENAM) Mirrors the Loss of Enamel in the Fossil Record of Placental Mammals. 2009. R.W. Meredith, et al. PLoS Genet 5(9): e1000634.
Biologists report new evidence for evolutionary change recorded in both the fossil record and the genomes (or genetic blueprints) of living organisms, providing fresh support for Charles Darwin's theory of evolution.
The researchers were able to correlate the progressive loss of enamel in the fossil record with a simultaneous molecular decay of a gene, called the enamelin gene, that is involved in enamel formation in mammals.

Paintings by Carl Buell. (c) John Gatesy & Carl Buell.
The researchers conducted a study where they predicted that living enamelless mammals would have copies of the gene that codes for the tooth-specific enamelin protein, but this gene would show evidence of molecular decay in these species.

"Mammals without enamel are descended from ancestral forms that had teeth with enamel," Springer said. "We predicted that enamel-specific genes such as enamelin would show evidence in living organisms of molecular decay because these genes are vestigial and no longer necessary for survival."

Using modern gene sequencing technology, Meredith discovered mutations in the enamelin gene that disrupt how the enamelin protein is coded, resulting in obliteration of the genetic blueprint for the enamelin protein.

Darwin argued that all organisms are descended from one or a few organisms and that natural selection drives evolutionary change. The fossil record demonstrates that the first mammals had teeth with enamel. Mammals without enamel therefore must have descended from mammals with enamel-covered teeth.

"The molecular counterpart to vestigial organs is pseudogenes that are descended from formerly functional genes," Springer explained. "In our research we clearly see the parallel evolution of enamel loss in the fossil record and the molecular decay of the enamelin gene into a pseudogene in representatives of four different orders of mammals that have lost enamel." link

I Am A Palaeontologist

Thursday, September 03, 2009

Lamarkian Evolution and the Origin of Epigenetics

Did Paul Kammerer discover epigenetic inheritance? A modern look at the controversial midwife toad experiments. 2009. Journal of Experimental Zoology.
A new study into the research of the Lamarckian experimentalist Paul Kammerer may help to end the controversy which has engulfed his research for almost a century. The study suggests that far from being a fraud Kammerer may have discovered the field of epigenetics, placing him decades ahead of his contemporaries.
Paul Kammerer, a leading proponent of the Lamarckian theory of evolution, achieved global prominence in the 1920's by arguing that acquired traits could be passed down through generations. In his most controversial experiment, Kammerer forced midwife toads, a species that lives and mates on land, to live in water. Their offspring preferred to live and mate in water and by the third generation he noted that they began to develop black nuptial pads on their forelimbs, a feature common to water dwelling species.

In 1926 Kammerer fell into disgrace when it was found that his only remaining fixed specimen had been injected with India ink to produce the appearance of the black nuptial pads. Kammerer's own role in the alleged fraud has never been proven, but six weeks after its discovery he committed suicide. Eventually, a naturally occurring specimen with nuptial pads was found, demonstrating that midwife toads do have the potential to develop them.

Rexamination of Kammerer's experiments finding remarkable resemblances to newly discovered aspects of epigenetics, a flourishing new field of science which studies influences in inheritance beyond the DNA sequence.

Vargas has studied Kammerer's evidence, as summarized in his 1920's research notes, and found that Kammerer reported hybrid crosses of treated and untreated toads in which 'parent-of-origin effects' can be observed, a recurrent phenomenon in epigenetics. Kammerer also reported that his toads developed larger bodies than untreated land toads and that their eggs were smaller and contained less egg-yolk than normal. These are traits that are known to be influenced by epigenetic mechanisms. Building on these observations Vargas proposes a preliminary model based on current knowledge of epigenetics to explain the midwife toad experiments, which illustrates how in a modern context an explanation can be offered for results which appeared utterly mysterious to Kammerer and his contemporaries.

Kammerer's consistency with current epigenetic mechanisms provides new and compelling biological arguments in favour of the authenticity of the midwife toad experiments. link

Wednesday, September 02, 2009

The 1st Dog

mtDNA Data Indicates a Single Origin for Dogs South of Yangtze River, less than 16,300 Years Ago, from Numerous Wolves. 2009. J.-F.Pang, et al. MBE Advance Access published on Sept. 1, 2009.

New research has established that the dog arrived 16,000 years ago in Asia, south of the Yangtze River in China.
The point in time when the dog emerged is well in line with the point when the population of this part of the world changed from hunting and gathering to farming as a way of life – this was 10,000 to 12,000 years ago.

This research indicates that the dog has only one geographical origin, but is descended from a large number of animals. At least several hundred tame wolves, probably even more.

"Considering that it involved so many wolves, this indicates that this event was important and a major part of the culture," he asserts.

He adds that research results have produced several exciting theories such as the fact that the original dog, in contrast to its younger relatives in Europe who were used for herding and as guard dogs, probably ended up in people’s stomachs! link.

Tuesday, September 01, 2009

Gobi Photos #8

Here's the last set of photos from my recent trip into the Gobi with the Mongolian Academy of Sciences, Paleontological Center, and the Montessori High School at University Circle in Cleveland. The students should all be back in NA by now, while Caleb, David and I are doing research at the Paleo Lab for the rest of the week.

Tugrekenshire, where we spent a few hours on our last day in the gobi.

Mattie (stretched out, right) found a poached Protoceratops skeleton. The poachers had taken the skull but left the body. If you look close you can see some of the ribs; the two long bones in the bottom of the pit are the hips. Like many of the Proto skeletons at the site the animal is preserved with the body pointing up.

Back in UB we toured the Orchlon School. One teacher and two students from the school joined us on the trip and helped the students get a better understanding of Mongolian culture.

Caleb prepares himself for his upcoming Ph.D. in Dr. Evans lab.

Our wrap up lunch at the UB Hotel.

We ended out gobi trip watching the sun go down on the Flaming Cliffs.

Next year I'm planning on coming back to the Gobi again with Nomadic Expeditions. If you'd like to join the trip contact them or drop me a line

Debuted This Day: Creatures That Time Forgot