From Today In Science History:
In 1936, London's famed Crystal Palace, constructed for the International Exhibition of 1851, was destroyed in the most spectacular fire seen in Britain for many years. It started about 8 pm and spread with such amazing rapidity that within half an hour the great building was ablaze from end to end. Flames rose 300-ft despite the efforts of 90 engines and 500 firemen. Only the two towers escaped destruction. When built, constructed mainly of glass and iron, it was nicknamed "The Crystal Palace" by Punch magazine.
In 1854 the sculptor Benjamin Waterhouse Hawkins installed three construct full-size concrete restorations of Iguanodon, Hylaeosaurus, and Megalosaurus on the grounds of Sydenham Park, home of the Crystal Palace.
Sunday, November 30, 2008
Friday, November 28, 2008
Born This Day: Dunkinfield Henry Scott
Nov. 28, 1854 – Jan. 29, 1934
Scott continued writing papers after Williamson's death and in which he described many otherwise unknown fossil plants. He wrote the classic Studies in Fossil Botany, which greatly popularized the subject.
From Today In Science History
Painting by Mary Parrish
Scott was an English paleobotanist and leading authority of his time on the structure of fossil plants, one of those who laid the foundations of paleobotany. He conducted experiments in the Jodrell Laboratory in Kew Gardens, where he became its honorary keeper (1892-1906). In collaboration with W.C. Williamson, he wrote three papers on fossil-plant morphology (1894-95).Scott continued writing papers after Williamson's death and in which he described many otherwise unknown fossil plants. He wrote the classic Studies in Fossil Botany, which greatly popularized the subject.
From Today In Science History
Died This Day: Karl Ernst von Baer
Feb 29, 1792 - Nov 28, 1876
Von Baer was a Prussian-Estonian embryologist who discovered the mammalian egg (1827) and the notochord. He established the new science of comparative embryology alongside
comparative anatomy with the publication of two landmark volumes (in 1828 and 1837) covering the range of existing knowledge of the prebirth developments of vertebrates.
He showed that mammalian eggs were not the follicles of the ovary but microscopic particles inside the follicles. He described the development of the embryo from layers of tissue, which he called germ layers, and demonstrated similarities in the embryos of different species of vertebrates.
From Today In Science History
Von Baer was a Prussian-Estonian embryologist who discovered the mammalian egg (1827) and the notochord. He established the new science of comparative embryology alongside
comparative anatomy with the publication of two landmark volumes (in 1828 and 1837) covering the range of existing knowledge of the prebirth developments of vertebrates. He showed that mammalian eggs were not the follicles of the ovary but microscopic particles inside the follicles. He described the development of the embryo from layers of tissue, which he called germ layers, and demonstrated similarities in the embryos of different species of vertebrates.
From Today In Science History
Thursday, November 27, 2008
Odontochelys semitestacea: The Oldest Turtle
An ancestral turtle from the Late Triassic of southwestern China. 2008. Chun Li, et al. Nature 456: 497-501
Evidence supports the notion that turtle shells are bony extensions of their backbones and ribs that expanded and grew together to form a hard protective covering.
The fossilized turtle ancestor, dubbed Odontochelys semitestacea (translation: half-shelled turtle with teeth), likely lived in the water rather than on land.
Prior to discovery of Odontochelys, the oldest known turtle specimen was Proganochelys, which was found in Germany. Because Proganochelys has a fully-formed shell, it provides little information about how shells were formed. Odontochelys is older than Proganochelys and is helpful because it has only a partial shell, Rieppel said.
Odontochelys dorsal view
Odontochelys has no osteoderms and it has a partial shell extending from its backbone. It also shows a widening of ribs. Although Odontochelys has only a partial shell protecting its back, it does have a fully formed plastron – complete protection of its underside – just as turtles do today.
Odontochelys dorsal view
This strongly suggests Odontochelys was a water dweller whose swimming exposed its underside to predators, Rieppel said. "Reptiles living on the land have their bellies close to the ground with little exposure to danger," he said.
"This animal tells people to forget about turtle ancestors covered with osteoderms," he said.
The discovery in China of the oldest known turtle fossil, estimated at 220- million-years-old, gives scientists a clearer picture of how the turtle got its shell.From the press release:
Evidence supports the notion that turtle shells are bony extensions of their backbones and ribs that expanded and grew together to form a hard protective covering.
The fossilized turtle ancestor, dubbed Odontochelys semitestacea (translation: half-shelled turtle with teeth), likely lived in the water rather than on land.
Prior to discovery of Odontochelys, the oldest known turtle specimen was Proganochelys, which was found in Germany. Because Proganochelys has a fully-formed shell, it provides little information about how shells were formed. Odontochelys is older than Proganochelys and is helpful because it has only a partial shell, Rieppel said.
Odontochelys dorsal view
Odontochelys dorsal view
"This animal tells people to forget about turtle ancestors covered with osteoderms," he said.
Note: I did try to get a photo of the turtle for the blog. The press release says to contact the Field Museum's press person whose automatic e-mail reply states that they're out of the office until next Monday. Brilliant.
Our old friend Xiao-chun Wu from the Canadian Museum of Nature is a co-author on the paper. They'll have their press release posted tomorrow.
Update: Thanks to Dan at the CMN for the photos!
Congratulations to Victoria Arbour (U of Alberta)
A belated, but hearty, congratulations to Victoria Arbour from Phil Currie's lab at the University of Alberta for successfully defending her M.Sc. thesis, "Evolution, biomechanics, and function of the tail club of ankylosaurid dinosaurs (Ornithischia: Thyreophora)".
Wednesday, November 26, 2008
Plate Tectonics 4 Billion Years Old
Low heat flow inferred from >4 Gyr zircons suggests Hadean plate boundary interactions. 2008. M. Hopkins et al. Nature 456: 493-496.
From the press release:
"Unlike the longstanding myth of a hellish, dry, desolate early Earth with no continents, it looks like as soon as the Earth formed, it fell into the same dynamic regime that continues today," Harrison said. "Plate tectonics was inevitable, life was inevitable. In the early Earth, there appear to have been oceans; there could have been life — completely contradictory to the cartoonish story we had been telling ourselves."
The research is based on their analysis of ancient mineral grains known as zircons found inside molten rocks, or magmas, from Western Australia that are about 3 billion years old. The analysis determined that some of the zircons found in the magmas were more than 4 billion years old. They were also found to have been formed in a region with heat flow far lower than the global average at that time.
"The global average heat flow in the Earth's first 500 million years was thought to be about 200 to 300 milliwatts per meter squared," Hopkins said. "Our zircons are indicating a heat flow of just 75 milliwatts per meter squared — the figure one would expect to find in subduction zones, where two plates converge, with one moving underneath the other."
Evidence for water on Earth during the planet's first 500 million years is now overwhelming, according to Harrison. "You don't have plate tectonics on a dry planet," he said.
From the press release:
A new picture of the early Earth is emerging, including the surprising finding that plate tectonics may have started more than 4 billion years ago — much earlier than scientists had believed."We are proposing that there was plate-tectonic activity in the first 500 million years of Earth's history," said geochemistry professor Mark Harrison.
"Unlike the longstanding myth of a hellish, dry, desolate early Earth with no continents, it looks like as soon as the Earth formed, it fell into the same dynamic regime that continues today," Harrison said. "Plate tectonics was inevitable, life was inevitable. In the early Earth, there appear to have been oceans; there could have been life — completely contradictory to the cartoonish story we had been telling ourselves."
The research is based on their analysis of ancient mineral grains known as zircons found inside molten rocks, or magmas, from Western Australia that are about 3 billion years old. The analysis determined that some of the zircons found in the magmas were more than 4 billion years old. They were also found to have been formed in a region with heat flow far lower than the global average at that time.
"The global average heat flow in the Earth's first 500 million years was thought to be about 200 to 300 milliwatts per meter squared," Hopkins said. "Our zircons are indicating a heat flow of just 75 milliwatts per meter squared — the figure one would expect to find in subduction zones, where two plates converge, with one moving underneath the other."
Evidence for water on Earth during the planet's first 500 million years is now overwhelming, according to Harrison. "You don't have plate tectonics on a dry planet," he said.
Died This Day: Sven Anders Hedin
Feb. 19,1865 - Nov. 26, 1952
Hedin 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
Hedin 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
Died This Day: Nicolaus Steno
Jan. 10 – Nov. 26, 1686
Steno (a.k.a. Niels Steensen, or Stensen) was a Danish geologist and anatomist who first made unprecedented discoveries in anatomy, then established
some of the most important principles of modern geology. He was Danish royal anatomist for 2 years.
Interested by the characteristics and origins of minerals, rocks, and fossils, he published in Prodromus (1669) the law of superposition (if a series of sedimentary rocks has not been overturned, upper layers are younger and lower layers are older) and the law of original horizontality (although strata may be found dipping steeply, they were initially deposited nearly horizontal.) link image
Steno (a.k.a. Niels Steensen, or Stensen) was a Danish geologist and anatomist who first made unprecedented discoveries in anatomy, then established
some of the most important principles of modern geology. He was Danish royal anatomist for 2 years.Interested by the characteristics and origins of minerals, rocks, and fossils, he published in Prodromus (1669) the law of superposition (if a series of sedimentary rocks has not been overturned, upper layers are younger and lower layers are older) and the law of original horizontality (although strata may be found dipping steeply, they were initially deposited nearly horizontal.) link image
Tuesday, November 25, 2008
Evolutionary Origin of Live Birth
Clues to how animals switched from laying eggs to live birth may be found in the well-studied fruit fly’s ecology and genes.The fly is one of a dozen species of Drosophila to have recently had their genomes sequenced, information that should provide abundant opportunities for identifying genetic changes that cause females of this species, and not others, to retain their fertilized eggs until they are ready to hatch.
Even those Seychelles fly eggs that emerged unhatched were at an advanced state of development, the team reports in forthcoming issue of the Journal of Evolutionary Biology. Most larvae emerged within two hours compared to an average of nearly 23 hours for the other 10 species in the study.
Live birth could result from changes to the male reproductive strategy as well. Proteins found in the semen of the well-known lab fruit fly, Drosophila melanogaster, stimulate egg laying in the female. A modification of these signals could be responsible for the switch.
Early hatching offers advantages, the authors say. Mobile larvae can burrow into the ground to avoid becoming inadvertent hosts to the eggs of parasitic insects or a predator’s meal. But harboring offspring for a longer period of time costs the female.
One other fly in the study, Drosophila yakuba, also occasionally laid larvae instead of eggs, and their eggs also hatched fairly quickly, most in under 14 hours. It too specializes in a particular fruit, that of the Pandanus tree.
Monday, November 24, 2008
Published This Day: The Origin of the Species
From Today In Science History:
In 1859, The Origin of Species by Means of Natural Selection was published in England to great acclaim. In this groundbreaking book by British naturalist Charles Darwin, he argued that species are the result of a gradual biological evolution in which nature encourages, through natural selection, the propagation of those species best suited to their environments. This book is unquestionably one of the most influential in the history of science.
In 1859, The Origin of Species by Means of Natural Selection was published in England to great acclaim. In this groundbreaking book by British naturalist Charles Darwin, he argued that species are the result of a gradual biological evolution in which nature encourages, through natural selection, the propagation of those species best suited to their environments. This book is unquestionably one of the most influential in the history of science.
More Antediluvuan Ancestors
Click To Enlarge
Friday, November 21, 2008
Eileanchelys: Oldest Aquatic Turtle
A new stem turtle from the Middle Jurassic of Scotland: new insights into the evolution and palaeoecology of basal turtles. 2008. Anquetin et al. Proc. Royal Society B published on-line Tuesday, November 18, 2008.
From the press release:
The new turtle species Eileanchelys waldmani from the Middle Jurassic period (~164 million years old) from the Isle of Skye off the north-western coast of Scotland is the missing link between land-based and aquatic turtles. They were uncovered from rocks on the Isle of Skye by a team including researchers at University College London (UCL).
The oldest turtle fossils date from about 210 million years ago in the Late Triassic period and came from land-living rather than aquatic animals.
Eileanchelys was relatively small, with a shell around 20cm in length. It lived in lagoons and lakes alongside salamanders and sharks, in a habitat that was very different from today’s Isle of Skye.
Most modern turtles are aquatic and live in tropical areas of the world. There are about 300 species alive today and many of these are endangered.
The new turtle species Eileanchelys waldmani from the Middle Jurassic period (~164 million years old) from the Isle of Skye off the north-western coast of Scotland is the missing link between land-based and aquatic turtles. They were uncovered from rocks on the Isle of Skye by a team including researchers at University College London (UCL).
The oldest turtle fossils date from about 210 million years ago in the Late Triassic period and came from land-living rather than aquatic animals.
Ilustration of the oldest known aquatic turtle's habitat 160 million years ago on the Isle of Skye, Scotland
Most modern turtles are aquatic and live in tropical areas of the world. There are about 300 species alive today and many of these are endangered.
Thursday, November 20, 2008
Deep-Sea Protists Can Explain Precambian Traces
Giant Deep-Sea Protist Produces Bilaterian-like Traces. 2008. M. V. Mat. Current Biology 18, published ahead of print edition.
From the press release:
A new discovery challenges one of the strongest arguments in favor of the idea that animals with bilateral symmetry existed before their obvious appearance in the fossil record during the early Cambrian, some 542 million years ago. Researchers report the first evidence that trace fossils interpreted by some as the tracks of ancient bilaterians could have instead been made by giant deep-sea protists, like those that can still be found at the seafloor to this day.
From the press release:
A new discovery challenges one of the strongest arguments in favor of the idea that animals with bilateral symmetry existed before their obvious appearance in the fossil record during the early Cambrian, some 542 million years ago. Researchers report the first evidence that trace fossils interpreted by some as the tracks of ancient bilaterians could have instead been made by giant deep-sea protists, like those that can still be found at the seafloor to this day.
The giant deep sea protist, Gromia sphaerica, approaches three large cup corals growing on a half-buried sea urchin. Photo: Misha Matz
"Our paper gives the precedent of a protozoan that is motile, produces macroscopic traces, and has a large hydrostatically supported body," said Mikhail Matz. With these possibilities demonstrated, pretty much anything within the Precambrian fossil record can in principle be attributed to large protozoans, from the earliest traces and fossils of the Stirling formation that are 1.8 billion years old to the weird Ediacaran biota with which the Precambrian culminated."
Died This Day: Sir John William Dawson
October 30, 1820 - November 20, 1899
Dawson was a Canadian geologist who made numerous contributions to paleobotany
and extended the knowledge of Canadian geology. Dawson was born and raised in Pictou, Nova Scotia, where the many sandstone and coal formations provided fertile ground for his first scientific explorations, which culminated in the publication of Acadian Geology. He made many important discoveries of fossil life, great and small. These included fossil plants, trackways of lowly invertebrates, footprints, skeletons of reptiles and amphibians, millipedes and the earliest land snails. When the famous geologist Charles Lyell visited coal deposits in Pictou, Dawson acted as his guide.
In 1851, Dawson and Lyell teamed up again to examine the interiors of fossil tree trunks at Joggins,
Nova Scotia. They discovered the remains of some of the earliest known reptiles, Hylonomus lyelli, along with other rare fossils, propelling this part of the world into the international spotlight.
Dawson became principal of McGill College in Montreal in 1854, which he made into a reputable institution. He remained there, teaching geology and palaeontology and acting as librarian, until his retirement. One of his lifelong dreams was realized in 1882 when Peter Redpath gave money to McGill for the construction and establishment of a museum, naming Dawson as director. Today the Peter Redpath Museum of Natural History houses many specimens from Dawson's personal collection.
Info from HERE and HERE. Images from HERE and HERE.
Dawson was a Canadian geologist who made numerous contributions to paleobotany
and extended the knowledge of Canadian geology. Dawson was born and raised in Pictou, Nova Scotia, where the many sandstone and coal formations provided fertile ground for his first scientific explorations, which culminated in the publication of Acadian Geology. He made many important discoveries of fossil life, great and small. These included fossil plants, trackways of lowly invertebrates, footprints, skeletons of reptiles and amphibians, millipedes and the earliest land snails. When the famous geologist Charles Lyell visited coal deposits in Pictou, Dawson acted as his guide.In 1851, Dawson and Lyell teamed up again to examine the interiors of fossil tree trunks at Joggins,
Nova Scotia. They discovered the remains of some of the earliest known reptiles, Hylonomus lyelli, along with other rare fossils, propelling this part of the world into the international spotlight.Dawson became principal of McGill College in Montreal in 1854, which he made into a reputable institution. He remained there, teaching geology and palaeontology and acting as librarian, until his retirement. One of his lifelong dreams was realized in 1882 when Peter Redpath gave money to McGill for the construction and establishment of a museum, naming Dawson as director. Today the Peter Redpath Museum of Natural History houses many specimens from Dawson's personal collection.
Info from HERE and HERE. Images from HERE and HERE.
Wednesday, November 19, 2008
Scientists Sequence Woolly-Mammoth Genome
Sequencing the nuclear genome of the extinct woolly mammoth. 2008. Webb Miller et al. Nature 456: 387-390.
From the news release:
The team sequenced the mammoth's nuclear genome using DNA extracted from the hairs of a mammoth mummy that had been buried in the Siberian permafrost for 20,000 years and a second mammoth mummy that is at least 60,000-years-old. By using hair, the scientists avoided problems that have bedeviled the sequencing of ancient DNA from bones because DNA from bacteria and fungi, which always are associated with ancient DNA, can more easily be removed from hair than from bones. Another advantage of using hair is that less damage occurs to ancient DNA in hair because the hair shaft encases the remnant DNA like a biological plastic, thus protecting it from degradation and exposure to the elements.
"Our data suggest that mammoths and modern-day elephants separated around six-million years ago, about the same time that humans and chimpanzees separated," said Miller. "However, unlike humans and chimpanzees, which relatively rapidly evolved into two distinct species, mammoths and elephants evolved at a more gradual pace," added Schuster, who believes that the data will help to shed light on the rate at which mammalian genomes, in general, can evolve.
The team's new data also provide additional evidence that woolly mammoths had low genetic diversity. "We discovered that individual woolly mammoths were so genetically similar to one another that they may have been especially susceptible to being wiped out by a disease, by a change in the climate, or by humans," said Schuster.
While members of the team previously ruled out humans as a cause of extinction for at least one of the Siberian sub-populations -- the group appears to have gone extinct at least 45,000 years ago at a time when there were no humans living in Siberia -- much debate still remains regarding the causes of extinction for the other group and for those populations that lived in other places, such as North America.
From the news release:
Scientists have completed the first genome-wide sequence of an extinct animal - the woolly mammoth. They sequenced four billion DNA bases using next-generation DNA-sequencing instruments and a novel approach that reads ancient DNA highly efficiently.The dataset is 100 times more extensive than any other published dataset for an extinct species, demonstrating that ancient DNA studies can be brought up to the same level as modern genome projects.
The team sequenced the mammoth's nuclear genome using DNA extracted from the hairs of a mammoth mummy that had been buried in the Siberian permafrost for 20,000 years and a second mammoth mummy that is at least 60,000-years-old. By using hair, the scientists avoided problems that have bedeviled the sequencing of ancient DNA from bones because DNA from bacteria and fungi, which always are associated with ancient DNA, can more easily be removed from hair than from bones. Another advantage of using hair is that less damage occurs to ancient DNA in hair because the hair shaft encases the remnant DNA like a biological plastic, thus protecting it from degradation and exposure to the elements.
"Our data suggest that mammoths and modern-day elephants separated around six-million years ago, about the same time that humans and chimpanzees separated," said Miller. "However, unlike humans and chimpanzees, which relatively rapidly evolved into two distinct species, mammoths and elephants evolved at a more gradual pace," added Schuster, who believes that the data will help to shed light on the rate at which mammalian genomes, in general, can evolve.
The team's new data also provide additional evidence that woolly mammoths had low genetic diversity. "We discovered that individual woolly mammoths were so genetically similar to one another that they may have been especially susceptible to being wiped out by a disease, by a change in the climate, or by humans," said Schuster.
While members of the team previously ruled out humans as a cause of extinction for at least one of the Siberian sub-populations -- the group appears to have gone extinct at least 45,000 years ago at a time when there were no humans living in Siberia -- much debate still remains regarding the causes of extinction for the other group and for those populations that lived in other places, such as North America.
Zdeněk Burian Art Show In Rotterdam
If any readers in Rotterdam goes to this, please pick me up a show catalogue.
FYI to readers: I'm on the road this week. Postings will return to normal next week.
Sabre-Toothed Cat Dredged Up From The North Sea
From the BBC News:
The partial leg bone of a sabre-toothed cat, Homotherium crenatidens, has been dredged from the seabed by a trawler in the North Sea.The fossil, which is between one and two million years old and was found near the UK coast, is from a type of sabre-tooth called a scimitar cat. It is the furthest north this species has ever been found, and the first time remains have come from the North Sea.
The fossil remains of more common extinct beasts such as the mammoth are routinely recovered from the sea by trawlers. Beam trawlers use special gear to gently touch the sea bed, capturing flatfish lying in the sand. But this also stirs up shallow, buried fossil remains which can end up in the nets. In the Netherlands, trawlermen are paid up to 100 euros for such discoveries.
Read the press release
Tuesday, November 18, 2008
Mongolia In Montana
If you’re in or near Bozeman, Montana, this week you should take in ”Discover Mongolia at Montana State University” that’s going on all this week.
Bolortsetseg Minjin (below), a paleontologist from Mongolia who is currently a visiting scholar at the Museum of the Rockies, will kick off the Discover Mongolia week with a presentation about dinosaurs in Mongolia. Her talk is set for noon, Monday, Nov. 17, in SUB room 275.
The Oscar-nominated film "Mongol," the story of Genghis Khan, will be shown at 7 p.m. Wednesday, Nov. 19 at the SUB's Procrastinator Theater. Directed by Sergei Bodrov, the sweeping film tells the story of Khan, who was a slave before conquering half the world in the early 1200s.
Traditional Mongolian music, song and dance will be performed by Mongolian students at 7 p.m. Thursday, Nov. 20, in SUB Ballroom A. There are currently five students from Mongolia studying at MSU as well as three scholars and professors.
Mongolian students will read to area children at 10 a.m. Friday, Nov. 21, at the Bozeman Public Library. The students will read from the book "The Khan's Daughter," as well as give a demonstration of Mongolian writing.
Mongolian cultural artifacts will be on display throughout the week at the MSU Library. In addition, an exhibition of the top 15 photographs taken by MSU students while on MSU's Study Abroad programs will be on display throughout International Education Week in the SUB's Exit Gallery. Paintings done by Mongolian children, ages 5-16, will be displayed at the Bozeman Public Library.
Friday, November 14, 2008
New Triceratops at Boston's Museum of Science
Remember the Triceratops up for auction in Paris last January? Apparently it was purchased for $942,797 and donated to the Museum of Science in Boston. It'll go on display there tomorrow. Andrew Waber from MOS Media Relations sent me this link to the YouTube video of it's timelapsed installation (~ 2min.).
Mineral Kingdom Has Co-Evolved With Life
Mineral evolution. R. M. Hazen et al. American Mineralogist 93: 1693
"It's a different way of looking at minerals from more traditional approaches," says Hazen. "Mineral evolution is obviously different from Darwinian evolution—minerals don't mutate, reproduce or compete like living organisms. But we found both the variety and relative abundances of minerals have changed dramatically over more than 4.5 billion years of Earth's history."
All the chemical elements were present from the start in the Solar Systems' primordial dust, but they formed comparatively few minerals. Only after large bodies such as the Sun and planets congealed did there exist the extremes of temperature and pressure required to forge a large diversity of mineral species. Many elements were also too dispersed in the original dust clouds to be able to solidify into mineral crystals.
As the Solar System took shape through "gravitational clumping" of small, undifferentiated bodies—fragments of which are found today in the form of meteorites—about 60 different minerals made their appearance. Larger, planet-sized bodies, especially those with volcanic activity and bearing significant amounts of water, could have given rise to several hundred new mineral species. Mars and Venus, which Hazen and coworkers estimate to have at least 500 different mineral species in their surface rocks, appear to have reached this stage in their mineral evolution.
However, only on Earth—at least in our Solar System—did mineral evolution progress to the next stages. A key factor was the churning of the planet's interior by plate tectonics, the process that drives the slow shifting continents and ocean basins over geological time. Unique to Earth, plate tectonics created new kinds of physical and chemical environments where minerals could form, and thereby boosted mineral diversity to more than a thousand types.
What ultimately had the biggest impact on mineral evolution, however, was the origin of life, approximately 4 billion years ago. "Of the approximately 4,300 known mineral species on Earth, perhaps two thirds of them are biologically mediated," says Hazen. "This is principally a consequence of our oxygen-rich atmosphere, which is a product of photosynthesis by microscopic algae." Many important minerals are oxidized weathering products, including ores of iron, copper and many other metals.
Microorganisms and plants also accelerated the production of diverse clay minerals. In the oceans, the evolution of organisms with shells and mineralized skeletons generated thick layered deposits of minerals such as calcite, which would be rare on a lifeless planet.
"For at least 2.5 billion years, and possibly since the emergence of life, Earth's mineralogy has evolved in parallel with biology," says Hazen. "One implication of this finding is that remote observations of the mineralogy of other moons and planets may provide crucial evidence for biological influences beyond Earth."
Scientists have found that the mineral kingdom co-evolved with life, and that up to two thirds of the more than 4,000 known types of minerals on Earth can be directly or indirectly linked to biological activity.From the press release:
"It's a different way of looking at minerals from more traditional approaches," says Hazen. "Mineral evolution is obviously different from Darwinian evolution—minerals don't mutate, reproduce or compete like living organisms. But we found both the variety and relative abundances of minerals have changed dramatically over more than 4.5 billion years of Earth's history."
As the Solar System took shape through "gravitational clumping" of small, undifferentiated bodies—fragments of which are found today in the form of meteorites—about 60 different minerals made their appearance. Larger, planet-sized bodies, especially those with volcanic activity and bearing significant amounts of water, could have given rise to several hundred new mineral species. Mars and Venus, which Hazen and coworkers estimate to have at least 500 different mineral species in their surface rocks, appear to have reached this stage in their mineral evolution.
What ultimately had the biggest impact on mineral evolution, however, was the origin of life, approximately 4 billion years ago. "Of the approximately 4,300 known mineral species on Earth, perhaps two thirds of them are biologically mediated," says Hazen. "This is principally a consequence of our oxygen-rich atmosphere, which is a product of photosynthesis by microscopic algae." Many important minerals are oxidized weathering products, including ores of iron, copper and many other metals.
Microorganisms and plants also accelerated the production of diverse clay minerals. In the oceans, the evolution of organisms with shells and mineralized skeletons generated thick layered deposits of minerals such as calcite, which would be rare on a lifeless planet.
New Homo erectus Pelvis & Human Development
A Female Homo erectus Pelvis from Gona, Ethiopia. 2008. S. W. Simpson et al. Science 322: 1089 – 1092.
A reconstruction of the 1.2 million-year-old pelvis discovered in 2001 in the Gona Study Area at Afar, Ethiopia, that has led researchers to speculate early man was better equipped than first thought to produce larger-brained babies. The actual fossils remain in Ethiopia.
Reconstructing pelvis bone fragments from the 1.2 million-year-old adult female, Semaw and his co-workers determined the early ancestor's birth canal was more than 30 percent larger than earlier estimates based on a 1.5-million-year-old juvenile male pelvis found in Kenya. The new female fragments were discovered in the Gona Study Area in Afar, Ethiopia, in 2001 and excavation was completed in 2003.
Scientists also were intrigued by other unique attributes of the specimen, such as its shorter stature and broader body shape more likely seen in hominids adapted to temperate climates, rather than the tall and narrow body believed to have been efficient for endurance running.
Scientists had thought early adult Homo erectus females, because of the assumed small birth canal, would produce offspring with only a limited neonatal brain size. These young would have then experienced rapid brain growth while still developmentally immature, leading researchers to envision a scenario of maternal involvement and child-rearing on par with that of modern humans. But those theories had been based upon extrapolations from the existing male skeleton from Kenya.
Credit: Scott W. Simpson, Case Western Reserve University.
Discovery of the most intact female pelvis of Homo erectus may cause scientists to reevaluate how early humans evolved to successfully birth larger-brained babies.From the press release:
A reconstruction of the 1.2 million-year-old pelvis discovered in 2001 in the Gona Study Area at Afar, Ethiopia, that has led researchers to speculate early man was better equipped than first thought to produce larger-brained babies. The actual fossils remain in Ethiopia.
Reconstructing pelvis bone fragments from the 1.2 million-year-old adult female, Semaw and his co-workers determined the early ancestor's birth canal was more than 30 percent larger than earlier estimates based on a 1.5-million-year-old juvenile male pelvis found in Kenya. The new female fragments were discovered in the Gona Study Area in Afar, Ethiopia, in 2001 and excavation was completed in 2003.
Scientists also were intrigued by other unique attributes of the specimen, such as its shorter stature and broader body shape more likely seen in hominids adapted to temperate climates, rather than the tall and narrow body believed to have been efficient for endurance running.
Scientists had thought early adult Homo erectus females, because of the assumed small birth canal, would produce offspring with only a limited neonatal brain size. These young would have then experienced rapid brain growth while still developmentally immature, leading researchers to envision a scenario of maternal involvement and child-rearing on par with that of modern humans. But those theories had been based upon extrapolations from the existing male skeleton from Kenya.
Thursday, November 13, 2008
Gobi 2008: Deinocheirus
Back in the late 60's the Polish-Mongolian expedition discovered and collected the giant arms (see cast above) of the enigmatic theropod, Deinocheirus, known only from these arms. Near the end of the 2008 KID expedition Philip Currie discovered the location of the near-fabled Deinocheirus quarry (below) and we spent part of a day reopening it. And we did collect more of the skeleton...
Photo © M. Ryan
Tuesday, November 11, 2008
Reptiles & Birds Share Hair Genes
Identification of reptilian genes encoding hair keratin-like proteins suggests a new scenario for the evolutionary origin of hair. 2008. L. Eckhart. PNAS, Published online before print November 10, 2008
From the press release:
The origins of hair date back to an unknown reptile ancestor that lived more than 300 million years ago, in the Paleozoic era. The discovery was made by comparing human, chicken, and green anole lizard genomes. The genome of the lizard was found to contain six different genes for hair keratin, the protein from which mammal hair is made.
The genes were expressed most strongly in the lizard's toes, indicating that the first hair genes played a role in claw formation.
"At least two of these hair protein keratins are formed in the growth zones of the claws," Eckhart said. While the role of the anole lizard's four other hair genes remains unclear, they were likely related to the growth of scales, the study team said. The chicken genome revealed a single hair gene. It's unclear what that gene is for, if anything.
The finding suggests that modern birds, reptiles, and mammals—as well as dinosaurs—shared an early common ancestor that had claws built from hair keratin, Eckhart said.
From the press release:
The origins of hair date back to an unknown reptile ancestor that lived more than 300 million years ago, in the Paleozoic era. The discovery was made by comparing human, chicken, and green anole lizard genomes. The genome of the lizard was found to contain six different genes for hair keratin, the protein from which mammal hair is made.
The genes were expressed most strongly in the lizard's toes, indicating that the first hair genes played a role in claw formation.
"At least two of these hair protein keratins are formed in the growth zones of the claws," Eckhart said. While the role of the anole lizard's four other hair genes remains unclear, they were likely related to the growth of scales, the study team said. The chicken genome revealed a single hair gene. It's unclear what that gene is for, if anything.
The finding suggests that modern birds, reptiles, and mammals—as well as dinosaurs—shared an early common ancestor that had claws built from hair keratin, Eckhart said.
Monday, November 10, 2008
Mekanik Destruktiw Kommandoh
Not having a TV I'm out of the loop on what's new in commericals, so this might be old hat to you all.
Earth's Largest Rodent
The largest among the smallest: the body mass of the giant rodent Josephoartigasia monesi. 2008. V. Millien. Proc. Royal Soc. B.275: 1953-1955
One I missed last summer…:
The newly-identified Josephoartigasia monesi is believed to be the largest rodent ever to have walked the Earth, was about three meters long and 1.5 meters tall, and weighed from 468 kilos to 2.5 tonnes, according to researchers.
The remains of the skull was found in a broken boulder on Kiyu Beach on the coast of Uruguay's River Plate region. Measuring a whopping 53 cm, the skull has massive incisors several centimeters long.
Despite this fearsome look, the creature was not carnivorous and looked more hippo-like than rat-like. It was so big that it probably spent much of its life semi-submerged in water, to reduce the stresses caused by its size.
The largest living rodent is the carpincho or capybara that also lives in regions of South America and can weigh up to 60 kg. link
One I missed last summer…:
The newly-identified Josephoartigasia monesi is believed to be the largest rodent ever to have walked the Earth, was about three meters long and 1.5 meters tall, and weighed from 468 kilos to 2.5 tonnes, according to researchers.
The remains of the skull was found in a broken boulder on Kiyu Beach on the coast of Uruguay's River Plate region. Measuring a whopping 53 cm, the skull has massive incisors several centimeters long.
Despite this fearsome look, the creature was not carnivorous and looked more hippo-like than rat-like. It was so big that it probably spent much of its life semi-submerged in water, to reduce the stresses caused by its size.
The largest living rodent is the carpincho or capybara that also lives in regions of South America and can weigh up to 60 kg. link
Died This Day: Gideon Mantell
Feb. 3, 1790 – Nov. 10, 1852
Mantell, 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.
Mantell, 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.
Saturday, November 08, 2008
New Xenozoic Tales Print
This artwork is reproduced using the highest standards in printmaking. Schultz has hand selected the paper used and overseen every stage of production. He has personally approved the final prints.
Get it Here
Remember that Mark has a new colour dinosaur print available exclusively from the Palaeoblog. For more info go to this previous posting.
No Dino Dance Floor?
A group of paleontologists visited the northern Arizona wilderness site nicknamed a "dinosaur dance floor" and concluded there were no dinosaur tracks there, only a dense collection of unusual potholes eroded in the sandstone.
So the scientist who leads the University of Utah's geology department says she will team up with the skeptics for a follow-up study.
On Oct. 30 – more than a week after the Utah study was publicized worldwide – four scientists hiked to the remote wilderness-area site: paleontologist Brent Breithaupt, director and curator of the University of Wyoming's Geological Museum; U.S. Bureau of Land Management paleontologist Alan Titus and geologist Rody Cox; and paleontologist Andrew Milner of the St. George (Utah) Dinosaur Discovery Site at Johnson Farm. They saw dinosaur tracks en route, but none in the pockmarked "dance floor."
Read the press release Here.
Friday, November 07, 2008
New Turok, Son of Stone
Veteran illustrator and dinosaur expert Pete Von Sholly has created an absolutely stunning series of trading cards depicting new, weird & mysterious covers for Turok: Son of Stone, with scientifically accurate dinosaurs, effectively updating this classic genre with fifty new pieces. Text on the back of the card tells details of the dinosaurs. This set will amaze and inform casual observers and serious Turok or dinosaur buffs alike.
Oh yeah, I'm on the road this week - postings will return to normal next week.
Died This Day: Alfred Russel Wallace
Jan. 8, 1823 – Nov. 7, 1913
From Today In Science History:
Wallace was a British naturalist and biogeographer. He was the first westerner to describe some of the most interesting natural habitats in the tropics. He is best known for devising a theory of the origin of species through natural selection made independently of Darwin.
Between 1854 and 1862, Wallace assembled evidence of natural selection in the Malay Archipelago, sending his conclusions to Darwin in England. Their findings were jointly presented to the Linnaean Society in 1858. Wallace found that Australian species were more primitive, in evolutionary terms, than those of Asia, and that this reflected the stage at which the two continents had become separated. He proposed an imaginary line (now known as Wallace's line) dividing the fauna of the two regions.
The Alfred Russel Wallace page HERE. More HERE.
From Today In Science History:
Wallace was a British naturalist and biogeographer. He was the first westerner to describe some of the most interesting natural habitats in the tropics. He is best known for devising a theory of the origin of species through natural selection made independently of Darwin.
Between 1854 and 1862, Wallace assembled evidence of natural selection in the Malay Archipelago, sending his conclusions to Darwin in England. Their findings were jointly presented to the Linnaean Society in 1858. Wallace found that Australian species were more primitive, in evolutionary terms, than those of Asia, and that this reflected the stage at which the two continents had become separated. He proposed an imaginary line (now known as Wallace's line) dividing the fauna of the two regions.The Alfred Russel Wallace page HERE. More HERE.
Thursday, November 06, 2008
Died This Day: Henry Fairfield Osborn
August 8, 1857 - November 6, 1935
Osborn graduated at Princeton in 1877 and pursued his interest in the biological sciences and paleontology through additional study at several New York City medical schools and with Thomas Henry Huxley in Britain.
Returning to the United States, Osborn accepted a position at Princeton, teaching natural sciences from 1881 until 1891, when he moved to Columbia University to organize the Biology Department there, and in 1891, he also helped to organize the Department of Vertebrate Paleontology at the American Museum of Natural History acting as it’s first curator. Osborn's close association with American Museum continued for over 45 years, and included a long tenure as its President, 1908-1933. During these years the museum's collections expanded enormously and it became one of the preeminent research institutions for natural history in the world.
Osborn is noted for describing and naming both Tyrannosaurus rex and Albertosaurus in 1905, Pentaceratops in 1923, and Velociraptor in 1924. One of Osborn's favorite groups for study was the brontotheres, and he was the first to carry out comprehensive research on them. He also wrote an influential textbook, The Age of Mammals (1910).
Apart from his own research, Osborn is perhaps best remembered for the sponsorship of the five immensely successful Central Asiatic Expeditions during the 1920's and 30's led by Roy Chapman Andrews.
Entry from HERE and HERE.
Osborn graduated at Princeton in 1877 and pursued his interest in the biological sciences and paleontology through additional study at several New York City medical schools and with Thomas Henry Huxley in Britain.
Returning to the United States, Osborn accepted a position at Princeton, teaching natural sciences from 1881 until 1891, when he moved to Columbia University to organize the Biology Department there, and in 1891, he also helped to organize the Department of Vertebrate Paleontology at the American Museum of Natural History acting as it’s first curator. Osborn's close association with American Museum continued for over 45 years, and included a long tenure as its President, 1908-1933. During these years the museum's collections expanded enormously and it became one of the preeminent research institutions for natural history in the world.Osborn is noted for describing and naming both Tyrannosaurus rex and Albertosaurus in 1905, Pentaceratops in 1923, and Velociraptor in 1924. One of Osborn's favorite groups for study was the brontotheres, and he was the first to carry out comprehensive research on them. He also wrote an influential textbook, The Age of Mammals (1910).
Apart from his own research, Osborn is perhaps best remembered for the sponsorship of the five immensely successful Central Asiatic Expeditions during the 1920's and 30's led by Roy Chapman Andrews.
Entry from HERE and HERE.
Monday, November 03, 2008
Body Size Evolution In Mesozoic Birds
Body size evolution in Mesozoic birds: little evidence for Cope's rule. 2008. R. BUTLER & A. GOSWAMI. Journal of Evolutionary Biology 21: 1673–1682.
We here reassess the results of this study, and additionally carry out novel analyses testing for within-lineage patterns in body size evolution in Mesozoic birds. We demonstrate that the nonphylogenetic methods used by this previous study cannot distinguish between among- and within-lineage processes, and that statistical support for their results and conclusions is extremely weak.
Our ancestor–descendant within-lineage analyses explicitly incorporate recent phylogenetic hypotheses and find little compelling evidence for Cope's rule. Cope's rule is not supported in Mesozoic birds by the available data, and body size evolution currently provides no insights into avian survivorship through the Cretaceous–Paleogene mass extinction.
Image:Todd Marshall
ABSTRACT: Cope's rule, the tendency towards evolutionary increases in body size, is a long-standing macroevolutionary generalization that has the potential to provide insights into directionality in evolution; however, both the definition and identification of Cope's rule are controversial and problematic. A recent study [J. Evol. Biol. 21 (2008) 618] examined body size evolution in Mesozoic birds, and claimed to have identified evidence of Cope's rule occurring as a result of among-lineage species sorting.We here reassess the results of this study, and additionally carry out novel analyses testing for within-lineage patterns in body size evolution in Mesozoic birds. We demonstrate that the nonphylogenetic methods used by this previous study cannot distinguish between among- and within-lineage processes, and that statistical support for their results and conclusions is extremely weak.
Our ancestor–descendant within-lineage analyses explicitly incorporate recent phylogenetic hypotheses and find little compelling evidence for Cope's rule. Cope's rule is not supported in Mesozoic birds by the available data, and body size evolution currently provides no insights into avian survivorship through the Cretaceous–Paleogene mass extinction.
Evolution of Conodonts
Evolution of morphogenesis in 360-million-year-old conodont chordates calibrated in days. 2008. Jerzy Dzik. Evolution & Development 10: 769 - 777
ABSTRACT: Highly rhythmic increments of crown tissue are identifiable in conodont oral apparatus elements from the Late Devonian of the Holy Cross Mountains, Poland; individual laminae being of thickness comparable with daily increments of vertebrate tooth enamel and fish otoliths. Abundant occurrence of such specimens enables bed-by-bed (stratophenetic) studies of the process of evolution at the population level and quantitative presentation of the evolution of ontogeny in the sampled geological section covering several million years.
The morphologic transformation is expressed as expansion of a juvenile asymmetry to later stages of the ontogeny and in decrease of the mature element width, which was due to a change of the mineral tissue secretion rate. It was not just a simple extension of a juvenile character into the later stage of the ontogeny (heterochrony) but rather a true developmental novelty. The evolution was gradual and very slow. The proposed quantitative approach to growth increments in the mineral skeleton of ancient chordates introduces real-time units to evolutionary developmental studies connected with direct paleontological evidence on the course of evolution.
ABSTRACT: Highly rhythmic increments of crown tissue are identifiable in conodont oral apparatus elements from the Late Devonian of the Holy Cross Mountains, Poland; individual laminae being of thickness comparable with daily increments of vertebrate tooth enamel and fish otoliths. Abundant occurrence of such specimens enables bed-by-bed (stratophenetic) studies of the process of evolution at the population level and quantitative presentation of the evolution of ontogeny in the sampled geological section covering several million years.
The morphologic transformation is expressed as expansion of a juvenile asymmetry to later stages of the ontogeny and in decrease of the mature element width, which was due to a change of the mineral tissue secretion rate. It was not just a simple extension of a juvenile character into the later stage of the ontogeny (heterochrony) but rather a true developmental novelty. The evolution was gradual and very slow. The proposed quantitative approach to growth increments in the mineral skeleton of ancient chordates introduces real-time units to evolutionary developmental studies connected with direct paleontological evidence on the course of evolution.
Sunday, November 02, 2008
Died This Day: Oliver Perry Hay
May 22, 1846 – Novemeber 2, 1930
Hay was an American paleontologist whose catalogs of fossil vertebrates greatly organized existing knowledge and became standard references. Hay's primary scientific interest was the study of the Pleistocene vertebrata of North America and he is renowned for his work on skull and brain anatomy. His first major work was his Bibliography and Catalogue of the Fossil Vertebrata of North America (1902), supplemented by two more volumes (1929-30). Hay also wrote on the evidence of early humans in North America. link
Hay was an American paleontologist whose catalogs of fossil vertebrates greatly organized existing knowledge and became standard references. Hay's primary scientific interest was the study of the Pleistocene vertebrata of North America and he is renowned for his work on skull and brain anatomy. His first major work was his Bibliography and Catalogue of the Fossil Vertebrata of North America (1902), supplemented by two more volumes (1929-30). Hay also wrote on the evidence of early humans in North America. link
Saturday, November 01, 2008
Born This Day: John Joly
Nov. 1, 1857 - Dec. 8, 1933
From Today in Science History:
Joly was an Irish geologist, physicist and inventor whose interests spanned several fields. Using Edmond Halley's method of measuring the degree of salinity of the oceans, and then by examining radioactive decay in rocks, he estimated Earth's age at 80-90 million years (1898). Later, he revised this figure to 100 million years. He published Radioactivity and Geology (1909) in which he demonstrated that the rate of radioactive decay has been more or less constant through time. He also developed a method for extracting radium (1914) and pioneered its use for cancer treatment.
From Today in Science History:
Joly was an Irish geologist, physicist and inventor whose interests spanned several fields. Using Edmond Halley's method of measuring the degree of salinity of the oceans, and then by examining radioactive decay in rocks, he estimated Earth's age at 80-90 million years (1898). Later, he revised this figure to 100 million years. He published Radioactivity and Geology (1909) in which he demonstrated that the rate of radioactive decay has been more or less constant through time. He also developed a method for extracting radium (1914) and pioneered its use for cancer treatment.
Born This Day: Alfred Wegener
Nov. 1, 1880 – Nov, 1930
From Today In Science History:
From Today In Science History:
Visit The Paleomap Project
Alfred Lothar Wegener was a German meteorologist and geophysicist who first gave a well-developed hypothesis of continental drift. He suggested (1912) that about 250 million yrs ago all the present-day continents came from a single primitive land mass, the supercontinent Pangaea, which eventually broke up and gradually drifted apart. (A similar idea was proposed earlier by F.B. Taylor in 1910.) Others saw the fit of coastlines of South America and Africa, but Wegener added more geologic and paleontologic evidence that these two continents were once joined.
Born This Day: Gavin de Beer
Illo © Nick Longrich
Nov. 1, 1899 – June 21, 1972From Today In Science History:
de Beer was an English zoologist and morphologist who contributed to experimental embryology, anatomy, and evolution. He refuted the germ-layer theory and developed the concept of paedomorphism - the retention of juvenile characteristics of ancestors in mature adults).
From examination of the fossil Archaeopteryx, De Beer proposed mosaic evolution with piecemeal evolutionary changes to explain the combination of bird and reptile features.
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