Thursday, February 25, 2010

7 Gigantic Dinosaurs

Life will take me away from regular updates for a bit. Updates will not stop but they will be irregular. Things should return to normal in a week or two. And, the blog had its 5th anniversary a few weeks ago, so thanks for all the support!

Monday, February 22, 2010

Died This Day: Sir Charles Lyell

Nov. 14, 1797 - Feb. 22, 1875
From Minnesota State University at Mankato comes this excellent bio on Lyell:

Sir Charles Lyell attended Oxford University at age 19. Lyell's father was an active naturalist. Lyell had access to an elaborate library including subjects such as Geology.

When Lyell was at Oxford, his interests were mathematics, classics, law and geology. He attended a lecture by William Buckland that triggered his enthusiasm for geology. Lyell originally started his career as a lawyer, but later turned to geology. He became an author of The Geological Evidence of the Antiquity of Man in 1863 and Principles of Geology. Lyell argued in this book that, at the time, presently observable geological processes were adequate to explain geological history. He thought the action of the rain, sea, volcanoes and earthquakes explained the geological history of more ancient times.

Lyell rebelled against the prevailing theories of geology of the time. He thought the theories were biased, based on the interpretation of Genesis. He thought it would be more practical to exclude sudden geological catastrophes to vouch for fossil remains of extinct species and believed it was necessary to create a vast time scale for Earth's history. This concept was called Uniformitarianism. The second edition of Principles of Geology introduced new ideas regarding metamorphic rocks. It described rock changes due to high temperature in sedimentary rocks adjacent to igneous rocks. His third volume dealt with paleontology and stratigraphy. Lyell stressed that the antiquity of human species was far beyond the accepted theories of that time.

Charles Darwin became his dear friend and correspondent. Darwin is quoted saying, "The greatest merit of the Principles was that it altered the whole tone of one's mind, and therefore that, when seeing a thing never seen by Lyell, one yet saw it through his eyes."

Image from King’s College London.

Sunday, February 21, 2010

My Greatest Adventure!

Read the whole incredible tale HERE!

Texacephale langstoni

Texacephale langstoni, a new genus of pachycephalosaurid (Dinosauria: Ornithischia) from the upper Campanian Aguja Formation, southern Texas, USA. 2009. N. Longrich, et al. Cretaceous Research 31: 274-284.

Abstract [edit]: Recent work in the Campanian Aguja Formation of Big Bend, Texas, has resulted in the recovery of two frontoparietal domes from a new genus of pachycephalosaur. Texacephale langstoni gen. et sp. nov. is diagnosed by a tall, arched nasal boss, flange-like processes articulating the dome with the peripheral elements, and a low pedicel separating the cerebral fossa from the skull roof.

The phylogenetic analysis presented here indicates that the Asian pachycephalosaurs form a monophyletic group, deeply nested within the Pachycephalosauridae, and that the basal members of the group are all North American. This finding indicates that pachycephalosaurids originated in North America, rather than Asia, as previously believed.

The biology of Texacephale and other Pachycephalosauridae are also discussed. The morphology of the dome in Texacephale and other pachycephalosaurs supports the hypothesis that pachycephalosaurids engaged in intraspecific combat, while the occurrence of Texacephale and other pachycephalosaurs in nearshore deposits argues that the pachycephalosaurs were not restricted to inland habitats.

Saturday, February 20, 2010

Cenozoic Whale Evolution

Climate, Critters, and Cetaceans: Cenozoic Drivers of the Evolution of Modern Whales. 2010. F. G. Marx & M. D. Uhen. Science 327: 993-996.

Read the story at Atomic Surgery
Abstract [edit]: Modern cetaceans play an important role in the ocean ecosystem as apex predators and nutrient distributors, as well as evolutionary "stepping stones" for the deep sea biota.

Recent discussions on the impact of climate change and marine exploitation on current cetacean populations may benefit from insights into what factors have influenced cetacean diversity in the past.

Previous studies suggested that the rise of diatoms as dominant marine primary producers and global temperature change were key factors in the evolution of modern whales.

Based on a comprehensive diversity data set, we show that much of observed cetacean paleodiversity can indeed be explained by diatom diversity in conjunction with variations in climate as indicated by oxygen stable isotope records ( 18O)

Premiered This Day (1961): Reptilicus

Reptilicus (1961), has been described as the “Plan 9 from Outer Space” of giant monster movies and really has to be seen to be believed. It's the grand prize winner in the contest for “poster that is waaay better than the movie” – that wonderous art is by Reynold Brown, by the way.

Watch the Trailer

Friday, February 19, 2010

Ancient Plankton Feeders

100-Million-Year Dynasty of Giant Planktivorous Bony Fishes in the Mesozoic Seas. 2010. M. Friedman, et al. Science 327: 990-993.

Abstract: Large-bodied suspension feeders (planktivores), which include the most massive animals to have ever lived, are conspicuously absent from Mesozoic marine environments. The only clear representatives of this trophic guild in the Mesozoic have been an enigmatic and apparently short-lived Jurassic group of extinct pachycormid fishes.

Here, we report several new examples of these giant bony fishes from Asia, Europe, and North America. These fossils provide the first detailed anatomical information on this poorly understood clade and extend its range from the lower Middle Jurassic to the end of the Cretaceous, showing that this group persisted for more than 100 million years.

Modern large-bodied, planktivorous vertebrates diversified after the extinction of pachycormids at the Cretaceous-Paleogene boundary, which is consistent with an opportunistic refilling of vacated ecospace.

Read more at the Oxford Science Blog.

Born This Day: William Diller Matthew

Matthew (Feb. 19, 1871 – Sept. 24, 1930) was a superb mammalian paleontologist and important biogeographic theorist, and also G. G. Simpson's primary mentor. He 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.

Born This Day: Sven Anders Hedin

Hedin (Feb. 19,1865 - Nov. 26, 1952) was a Swedish explorer and geographer, born in Stockholm, who led four multi-year expeditions into Central Asia between 1897 and 1935. Although not as well known as Roy Chapman Andrews his work in the regions revealed a wealth of cultural, archaeological and palaeontological wonders.

During his first major Asian expedition, he crossed the Pamirs, charted Lop Nor (Lake) in China, and finally arrived at Beijing. He then journeyed to Tibet by way of Mongolia, Siberia, and the Gobi Desert. Hedin explored Tibet and Xinjiang (Sinkiang), identified the sources of the Brahmaputra, Indus, and Sutlej rivers, and, in 1906, explored and named the Trans-Himalayas. In 1927 Hedin led an expedition of Chinese and Swedish scientists into Central Asia.

He wrote extensively about his adventures (e.g., Across the Gobi Desert, The Conquest of Tibet (1935), My Life as an Explorer (1926)) and they make for engaging and fascinating reading for anyone interested in the early days of exploring Central Asia. link

An excellent summary of Hedin’s life and expeditions into Central Asia can be found at the IDP News Archives image

Born This Day: Sir Roderick Impey Murchison

Murchison (Feb. 19, 1792 - Oct. 22, 1871) was a Scottish geologist who first differentiated the Silurian strata in the geologic sequence of Early Paleozoic strata (408-540 million years old). He believed in fossils as primary criteria. In 1831, he began researching the previously geologically unknown graywacke rocks of the Lower Paleozoic, found underlying the Old Red Sandstone in parts of Wales, which culminated in his major work the Silurian System (1839).

An eurypterid, a prehistoric sea scorpion from
Murchison named the Silurian after an ancient British tribe that inhabited South Wales. He established the Devonian working with Adam Sedgwick (1839). He named the Permian (1841) after the Perm province in Russia where he made a geological survey in 1840-45. link

Thursday, February 18, 2010

Bistahieversor sealeyi

Two nearly complete skeletons of the new tyrannosauroid species, Bistahieversor sealeyi were discovered in the badlands of New Mexico's Bisti/De-na-zin Wilderness, and described in the latest volume of the Journal of Vertebrate Paleontology by Thomas Carr and Thomas Williamson

Read the story by C. Dell’Amore at National Geographic News. Sadly, JVP does not provide DOI links for their articles.

Premiered This Day (1938): Bringing Up Baby

When a man is wrestling a leopard in the middle of a pond, he's in no position to run.” Cary Grant as paleontologist David Huxley

Coming in at #97 on the American Film Institute's list of greatest films, ‘Bringing Up Baby’, co-starring Cary Grant and Kate Hepburn, is acknowledged as the archetypical screwball comedy.

Directed by Howard Hawks in 1938, Grant plays paleontologist David Huxley who is trying to secure a $1,000,000.00 endowment for his museum. He meets up with Hepburn’s seemingly scatterbrained heiress, Susan Vance, who becomes determined to derail Grant’s next day wedding.

Over the course of the next 24 hours Grant gets completely mired in Hepburn’s whirlwind ad hoc plans to catch her new (and completely reluctant) beau that includes hunting for her leopard (the ‘Baby’ of the title), having her steal his clothes, ending up in jail, falling in a stream, and finally losing his “intercostal clavicle” to Hepburn’s dog that was to be the final element needed complete the Brontosaurus skeleton he’s been working on for four years.

The fast-paced, witty script, sharp direction and comedic chemistry between Grant and Hepburn all combine to make this film worthy of multiple repeat viewings.


“The Triceracopter is half Triceratops, half helicopter. Built as a sculpture in 1977 by artist Patricia Renick, it's now available now for the discerning collector/dinopilot”. link.
Thanks to Toni for the link.

Died This Day: Adolphe-Théodore Brongniart

Adolphe-Théodore Brongniart (Jan. 14, 1801 - Feb. 18, 1876) was a French botanist whose classification of fossil plants drew surprisingly accurate relations between extinct and existing forms prior to Charles Darwin's principles of organic evolution. His work earned him the distinction as the founder of modern paleobotany.

He was an early proponent of evolutionary theory. Brongniart published the first complete account of fossil plants (1828). His interpretations of the fossil record also contributed to our understanding of historical changes in climates and plant geography. link image

Wednesday, February 17, 2010

60% Off Horned Dinosaurs

Today only, Indiana University Press is having a 60% off sale on all stock, including books yet to be published.

The Horned Dinosaur volume that I'm co-editing will, hopefully, be published very soon. Since the editors only get a couple of freebie copies for all our efforts, we not be able to give away copies to everyone who deserves one, as much as we would like to.

So, here's your chance to pre-order a copy at what will probably be the cheapest price you'll ever see it sold for.

The Origin of Insects

Arthropod relationships revealed by phylogenomic analysis of nuclear protein-coding sequences. 2010. J.C. C. Regier, et al. Nature, published online 10 February 2010

Speleonectes tulumensis is from a group of rare, blind, cave-dwelling crustaceans called remipede and are the crustaceans most closely related to the insects. Credit: Simon Richards
The new study supports the hypothesis that the insects evolved from a group of crustaceans. So flies, honeybees, ants, and crickets all branched off the arthropod family tree from within the lineage that gave rise to today's crabs, shrimp, and lobsters. Another important finding is that the "Chelicerata" (a group that includes the spiders, scorpions, ticks, and mites) branched off very early, earlier than the millipedes, centipedes, crustaceans, and insects. That means that the spiders, for example, are more distantly related to the insects than many researchers previously thought. link

Based on likelihood analyses of 62 nuclear protein-coding genes. Branch lengths are proportional to the amount of inferred sequence change, with the topology and analytical conditions identical to the degen1 analysis in Fig. 1. Line drawings of representatives of the major taxonomic groups show the morphological disparity across Arthropoda. Scale bar, nucleotide changes per site.

© DC Comics

Tuesday, February 16, 2010

Died Again This Day: Sandra Shaw

Although Sandra Shaw (May 27, 1913 – Feb. 16, 2000) had a short film career comprising a few, mostly uncredited film roles in 1933, her most famous appearance is that of the person plucked from her sleep from an unnamed hotel by King Kong, and than casually dropped to her death when he realizes that she is not Ann Darrow (Fay Wray). The year that Kong was released she married Gary Cooper.

Arbogast on Film blog has nice appreciation of Sandra Shaw’s few famous film moments.

Born This Day: Ernst Heinrich August Haeckel

Haeckel (Feb, 16, 1834 - Aug. 9, 1919) was a German zoologist and evolutionist who was a strong proponent of Darwinism and proposed new notions of the evolutionary descent of man. He coined many words commonly used by biologists today, such as phylum, phylogeny, and ecology.

He is noted for the book, The evolution of man: a popular exposition of the principal points of human ontogeny and phylogeny link

Born This Day: Jean-Baptiste-Julien d' Omalius d'Halloy

Feb. 16, 1783 - Jan. 15, 1875

d'Halloy was a Belgian geologist who was an early proponent of evolution and was acknowledged by Charles Darwin in his preface to ‘On The Origin of the Species’ for his opinions on the origin of new species through descent with modification.

He determined the stratigraphy of the Carboniferous and other rocks in Belgium and the Rhine provinces, and also made detailed studies of the Tertiary deposits of the Paris Basin. link

Sunday, February 14, 2010

Friday, February 12, 2010

The Ancient Human Genome

Ancient human genome sequence of an extinct Palaeo-Eskimo. 2010. M. Rasmussen, et al. Nature 463: 757-762.

Art by Nuka Godfredtsen; via National Geographic News
From the Editor’s Summary:
“For the first time, the sequence of a near-complete nuclear genome has been obtained from the tissue of an ancient human. It comes from permafrost-preserved hair, about 4,000 years old, of a male palaeo-Eskimo of the Saqqaq culture, the earliest known settlers in Greenland. Functional single-nucleotide polymorphism (SNP) assessment was used to assign possible phenotypic characteristics.

The analysis provides evidence for a migration from Siberia into the New World some 5,500 years ago, independent of the migration that gave rise to the modern Native Americans and Inuit. Elsewhere in the issue we profile the paper's last author Eske Willerslev, who headed the project and found the lock of hair in a Copenhagen museum basement — after a fruitless search among the archaeological sites of Peary Land.”

Born This Day: Barnum Brown

Feb. 12, 1873 – Feb. 5, 1963
Photo © AMNH
From the AMNH bio:

The greatest dinosaur hunter of the twentieth century was Barnum Brown, who began his career at the American Museum of Natural History in 1897 as an assistant to Henry Fairfield Osborn. Brown traveled all over the world collecting dinosaurs and fossil mammals. Some consider him to be the last of the great dinosaur hunters.

Brown was always impeccably dressed, often wearing a tie and topcoat even in the field. He was a shrewd "horse trader" when it came to wheeling and dealing for fossil specimens. Many of Brown's greatest discoveries, including the first specimens of Tyrannosaurus rex ever found, are displayed in the Museum's Dinosaur Halls.

Born This Day: Charles Darwin

Feb. 12, 1809 – April 19, 1882
Find out what's going on in your city to celebrate the 200th anniversary of Charles Darwin's birth HERE

From the AMNH introduction to their exhibit on Darwin:
Keenly observing nature in all its forms—from fossil sloths to mockingbirds, primroses to children—Darwin saw that we all are related. Every living thing shares an ancestry, he concluded, and the vast diversity of life on Earth results from processes at work over millions of years and still at work today. Darwin's explanation for this great unfolding of life through time—the theory of evolution by natural selection—transformed our understanding of the living world, much as the ideas of Galileo, Newton and Einstein revolutionized our understanding of the physical universe.

Darwin's theory of evolution by natural selection underlies all modern biology. It enables us to decipher our genes and fight viruses, and to understand Earth's fossil record and rich biodiversity. Simple yet at times controversial, misunderstood and misused for social goals, the theory remains unchallenged as the central concept of biology. Charles Darwin, reluctant revolutionary, profoundly altered our view of the natural world and our place in it.
The American Museum of Natural History's video on Darwin.

Darwin's biography from the British Library.
Learn more about Darwin Days.
The Darwin Awards.

Thursday, February 11, 2010

The Weapon Out of Time!

Read it at Atomic Surgery

Darwin Celebration 2010 at CWRU

Darwin Celebration 2010 continues here in Cleveland, Ohio, at Case Western Reserve University’s Darwin Celebration, an ongoing series of lectures and events that began in 2008 to celebrate Darwin's life and work by exploring how evolutionary biology informs current research in many fields of science.

Thursday February 11:

John Avise Seminar
"Inside the Human Genome: A Case for Non-Intelligent Design"
DeGrace Hall 312 4:15pm

John Avise is a world renowned biologist and author, and professor at the University of California, Irvine. Dr. Avise's laboratory conducts research using genetic markers to analyze the evolution of wild animals, from micro- to macro-evolutionary dynamics, phylogeography, speciation, systematics, and phylogenetics. The primary goal is to unveil ecological, behavioral, or evolutionary features of the organisms themselves; an important secondary concern is to elucidate molecular and evolutionary properties of protein and DNA molecules.

Friday February 12:

Phylogenetics Seminars
Wolstein Auditorium Wolstein Research Building

9:00am - Speaker: Helen Piontkivska
10:00am - Speaker: Rich Glor
11:30am - Speaker: Philip Gingerich
1:30pm - Speaker: John Avise

Saturday February 13:

Phylogenetics Workshop 9am - noon
Wolstein Research Building 4th floor conference room: 4-136.


Get more info on all the events HERE

Campus map HERE

The Formation of Prototaxites

Structural, physiological, and stable carbon isotopic evidence that the enigmatic Paleozoic fossil Prototaxites formed from rolled liverwort mats. 2010. L. E. Graham, et al. American Journal of Botany 97: 268-275.

Scenario for Prototaxites formation. Image courtesy of Kandis Elliot.
ABSTRACT [edit]: New structural, nutritional, and stable carbon isotope data may resolve a long-standing mystery—the biological affinities of the fossil Prototaxites, the largest organism on land during the Late Silurian to Late Devonian (420–370 Ma).

The tree trunk-shaped specimens, of varying dimensions but consistent tubular anatomy, first formed prior to vascular plant dominance. Hence, Prototaxites has been proposed to represent giant algae, fungi, or lichens, despite incompatible biochemical and anatomical observations.

Our comparative analyses instead indicate that Prototaxites formed (above) from partially degraded, wind-, gravity-, or water-rolled mats of mixotrophic liverworts having fungal and cyanobacterial associates, much like the modern liverwort genus Marchantia.

We propose that the fossil body is largely derived from abundant, highly degradation-resistant, tubular rhizoids of marchantioid liverworts, intermixed with tubular microbial elements.

Our interpretation indicates that liverworts were important components of Devonian ecosystems, that some macrofossils and microfossils previously attributed to "nematophytes" actually represent remains of ancient liverworts, and that mixotrophy and microbial associations were features of early land plants.

Wednesday, February 10, 2010

Bird-Dino Commentary From John Ruben

Paleobiology and the origins of avian flight. 2010. Published online before print February 9

“The weight of the evidence is now suggesting that not only did birds not descend from dinosaurs, Ruben said, but that some species now believed to be dinosaurs may have descended from birds.”
John Ruben has a commentary in PNAS on his ‘birds are not dinosaus’ ideas. link

Published This Day: 1st Paper to Recognize Fossils As Living Remains

From Today In Science History:

In 1667, a classic paleontological paper by Nicolaus Steno was published by the Royal Society, London. His topic, Head of a shark dissected, represented the first such scientific paper to recognise that fossils were the remains of creatures who had died and subsequently had become petrified. Controversy resulted as the same claim had been made in the time of the ancient Greeks, two millennia earlier.

Tuesday, February 09, 2010

Semi-Aquatic Spinosaurs?

Oxygen isotope evidence for semi-aquatic habits among spinosaurid theropods. 2010. R. Amio, et al., Geology 38: 139-142.

Abstract: Spinosaurs were large theropod dinosaurs showing peculiar specializations, including somewhat crocodile-like elongate jaws and conical teeth. Their biology has been much discussed, and a piscivorous diet has been suggested on the basis of jaw as well as tooth morphology and stomach contents.

Although fish eating has been considered plausible, an aquatic or semiaquatic lifestyle has seldom been suggested because of the apparent lack of corresponding adaptations in the postcranial skeleton of spinosaurs, which on the whole is reminiscent of that of other large terrestrial theropods.

On the basis of the oxygen isotopic composition of their phosphatic remains compared with those of coexisting terrestrial theropod dinosaurs and semiaquatic crocodilians and turtles, we conclude that spinosaurs had semiaquatic lifestyles, i.e., they spent a large part of their daily time in water, like extant crocodilians or hippopotamuses.

This result sheds light on niche partitioning between large predatory dinosaurs, since spinosaurs coexisted with other large theropods such as carcharodontosaurids or tyrannosaurids. The likely ichthyophagy and aquatic habits of spinosaurids may have allowed them to coexist with other large theropods by reducing competition for food and territory.

Ediacara Got Legs!

First evidence for locomotion in the Ediacara biota from the 565 Ma Mistaken Point Formation, Newfoundland. 2010. A. G. Liu, et al. Geology 38: 123-126.

Abstract: Evidence for locomotion in the Precambrian fossil record is scant. Reliable Ediacaran trace fossils are all younger than 560 Ma, and consist of relatively simple horizontal burrows and trails from shallow-water deposits.

Here we describe an assemblage of macroscopic locomotory traces from deep-water environments at Mistaken Point, southeastern Newfoundland, Canada, dated to ca. 565 Ma.

FF © Marvel Comics
These trails extend the record of complex trace fossils back into the earliest Avalonian biota. Our new evidence for large motile organisms on the seafloor at this time suggests that at least some of these early Ediacaran organisms, whose biological affinities are widely debated, could have been muscular and of metazoan grade.

Saturday, February 06, 2010

1st Dino App From The AMNH

The American Museum of National History has recently released the first official dinosaur app, Dinosaurs: American Museum of Natural History Collections, for iPhone users.

The Dinosaur app comprises more than 800 images from the Museum’s archive, woven together to create a striking image of the world’s most famous dinosaur, the Tyrannosaurus Rex.

Users can zoom into the mosaic and inspect individual photos, tap the info button to flip the photos and read stimulating information about the science and personalities of the Museum’s world-famous fossil collection. Each interactive photograph has information of where the fossil was found and the paleontologist who uncovered it. link

Download the app

Friday, February 05, 2010

Primordial Soup Did Not Cook Up 1st Life?

How did LUCA make a living? Chemiosmosis in the origin of life. 2010. N. Lane, et al. BioEassys, published Online: 27 Jan.

"Textbooks have it that life arose from organic soup and that the first cells grew by fermenting these organics to generate energy in the form of ATP. "We present the alternative that life arose from gases (H2, CO2, N2, and H2S) and that the energy for first life came from harnessing geochemical gradients created by mother Earth at a special kind of deep-sea hydrothermal vent – one that is riddled with tiny interconnected compartments or pores."

The soup theory was proposed in 1929 when J.B.S Haldane published his influential essay on the origin of life in which he argued that UV radiation provided the energy to convert methane, ammonia and water into the first organic compounds in the oceans of the early earth. However critics of the soup theory point out that there is no sustained driving force to make anything react; and without an energy source, life as we know it can't exist.

© Marvel Comics
In rejecting the soup theory the team turned to the Earth's chemistry to identify the energy source which could power the first primitive predecessors of living organisms: geochemical gradients across a honeycomb of microscopic natural caverns at hydrothermal vents. These catalytic cells generated lipids, proteins and nucleotides giving rise to the first true cells. link

Thursday, February 04, 2010

Haplocheirus sollers

A Basal Alvarezsauroid Theropod from the Early Late Jurassic of Xinjiang, China. 2010. J. N. Choiniere, et al. Science 327: 571 – 574.

Skull of Haplocheirus IVPP V15988 in dorsal view.
The discovery of Haplocheirus sollers (meaning simple, skillful hand) extends the fossil record of the family Alvarezsauridae – a bizarre group of bird-like dinosaurs with a large claw on the hand and very short, powerful arms – back 63 million years, further distancing the group from birds on the evolutionary tree. Until now, there was no direct evidence that dinosaurs of this type lived during the Late Jurassic, approximately 160 million years ago.

The new species shows some of the earliest evolutionary stages in the development of a short, powerful arm with a single functional claw that may have been used for digging termites.

Haplocheirus IVPP V15988 holotype specimen in right lateral view after skull was removed.
"Haplocheirus is a transitional fossil, because it shows an early evolutionary step in how the bizarre hands of later alvarezsaurs evolved from earlier predatory dinosaurs," said Mr. Choiniere. "The fossil also confirms our predictions that Alvarezsauridae should have been evolving in the Late Jurassic time period." link

Wednesday, February 03, 2010

Fish Heads, Fish Heads, Rolly Polly Fish Heads,...

Non-random decay of chordate characters causes bias in fossil interpretation. 2010. R. S. Sansom, et al. Nature, published online 31 January.

Credit: Mark Purnell, Rob Sansom, Sarah Gabbott, University of Leicester
These are three rotting heads. A sequence of images showing how the characteristic features of the body of amphioxus, a close living relative of vertebrates, change during decay. Colors are caused by interference between the experimental equipment and the light illuminating the specimens.

Palaeontologists have discovered that studying rotting fish sheds new light on our earliest ancestry.
The researchers devised a new method for extracting information from 500 million year old fossils - they studied the way fish decompose to gain a clearer picture of how our ancient fish-like ancestors would have looked. Their results indicate that some of the earliest fossils from our part of the tree of life may have been more complex than has previously been thought.

From the abstract [edit]: The experimental decay of amphioxus and ammocoetes show that loss of chordate characters during decay is non-random: the more phylogenetically informative are the most labile, whereas plesiomorphic characters are decay resistant. The taphonomic loss of synapomorphies and relatively higher preservation potential of chordate plesiomorphies will thus result in bias towards wrongly placing fossils on the chordate stem. Application of these data to Cathaymyrus (Cambrian period of China) and Metaspriggina (Cambrian period of Canada) highlights the difficulties: these fossils cannot be placed reliably in the chordate or vertebrate stem because they could represent the decayed remains of any non-biomineralized, total-group chordate. Preliminary data suggest that this decay filter also affects other groups of organisms and that ‘stem-ward slippage’ may be a widespread but currently unrecognized bias in our understanding of the early evolution of a number of phyla.

Translation: The results show that some of the characteristic anatomical features of early vertebrate fossils have been badly affected by decomposition, and in some cases may have rotted away completely. Knowing how decomposition affected the fossils means our reconstructions of our earliest ancestors will be more scientifically accurate. link

Born This Day: Gideon Mantell

Mantell (Feb. 3, 1790 – Nov. 10, 1852), a physician of Lewes in Sussex in southern England, had for years been collecting fossils in the sandstone of Tilgate forest, and he had discovered bones belonging to three extinct species: a giant crocodile, a plesiosaur, and Buckland's Megalosaurus. But in 1822 he found several teeth that "possessed characters so remarkable" that they had to have come from a fourth and distinct species of Saurian. After consulting numerous experts, Mantell finally recognized that the teeth bore an uncanny resemblance to the teeth of the living iguana, except that they were twenty times larger.
In this paper, the second published description of a dinosaur, he concluded that he had found the teeth of a giant lizard, which he named Iguanodon, or "Iguana-tooth."

Mantell illustrated his announcement with a single lithographed plate. Mantell included at the bottom of the plate a drawing of a recent iguana jaw, which is shown four times natural size, and for further comparison, he added views of the inner and outer surface of a single iguana tooth, "greatly magnified."

The traditional story that Mantell's wife found the first teeth in 1822, while the doctor was visiting a patient, appears, alas, to be unfounded.

Info and plate from HERE.

Died This Day: Ernst Mayr

July 5, 1904 - Feb. 3, 2005
Any student of biology, or anyone with an interest in the natural world, will be familiar with Ernst Mayr who passed away on February 3rd in Bedford, Mass. Born in Kempton, Germany he joined the American Museum of Natural History as a curator in 1931. In 1953 he left the museum to work at Harvard University where he stayed until his retirement in 1975.

While working on the problem of speciation in the birds of New Guinea, Mayr realized that the multitude of species and and subspecies that he saw could best be explained as being a snapshot of evolution in action. He suggested that new species could arise when the range of one species was fractured long enough for members in different parts of the range to evolve characters that would not allow individuals to reproduce when they were brought back together again. This lead to him developing the “biological species concept” in which species are defined as populations of interbreeding organisms rather than just a collection of characters. This idea, along with his theory of “allopatric speciation” was published in his book “Systematics and the Origin of the Species” (1942) and later contributed to the “Punctuated Equilibrium” theory of Niles Eldredge and Stephen Jay Gould.

Ernst Mayr was himself inspired by the work of geneticist Theodosius Dobzhansky on the fruit fly Drosophila melanogaster and his book “Genetics and the Origin of the Species” (1937). These two men, together with the paleontologist George Gaylord Simpson, combined the sciences of genetics, zoology and paleontology into what is now known as “the new synthesis” that provides the modern experimental underpinning to the concepts that Charles Darwin presented in his book, “On the Origin of the Species” .

For anyone interested in learning more about modern evolutionary theory I’d recommend Mayr’s recent book “What Evolution Is” (2002). It’s written in an engaging and readable format from the perspective of someone who’s thought about evolution all his life.

This Day In History: 1st Australopithecus africanus Announced

On this day in 1925 Raymond Dart announced the find of the “Taung child”, Australopithecus africanus, in The Star newspaper of Johannesburg, South Africa. Mr. Dart with his students made the find in the Taung limestone works in the Harts Valley of Bechuanaland. link