Photos © M. Ryan
Update: Jordan Mallon informs me that it’s an Albertosaurus that was sculpted by Russell Zeid entirely of scraps from junkyards around Alberta.
Saturday, March 31, 2007
Chinook Center T. rex Albertosaurus
Update: Jordan Mallon informs me that it’s an Albertosaurus that was sculpted by Russell Zeid entirely of scraps from junkyards around Alberta.
Friday, March 30, 2007
Floral Gigantism Strikes Back
Floral Gigantism in Rafflesiaceae. 2007. C. C. Davis, et al. Science 315: 1812
Abstract: Species of Rafflesiaceae possess the world's largest flowers (up to 1 meter in diameter), yet their precise evolutionary relationships have been elusive, hindering our understanding of the evolution of their extraordinary reproductive morphology.
We present results of phylogenetic analyses of mitochondrial, nuclear, and plastid data showing that Rafflesiaceae are derived from within Euphorbiaceae, the spurge family. Most euphorbs produce minute flowers, suggesting that the enormous flowers of Rafflesiaceae evolved from ancestors with tiny flowers.
Given the inferred phylogeny, we estimate that there was a circa 79-fold increase in flower diameter on the stem lineage of Rafflesiaceae, making this one of the most dramatic cases of size evolution reported for eukaryotes.
Return of the Giant Hogweed:
Abstract: Species of Rafflesiaceae possess the world's largest flowers (up to 1 meter in diameter), yet their precise evolutionary relationships have been elusive, hindering our understanding of the evolution of their extraordinary reproductive morphology.
We present results of phylogenetic analyses of mitochondrial, nuclear, and plastid data showing that Rafflesiaceae are derived from within Euphorbiaceae, the spurge family. Most euphorbs produce minute flowers, suggesting that the enormous flowers of Rafflesiaceae evolved from ancestors with tiny flowers.
Given the inferred phylogeny, we estimate that there was a circa 79-fold increase in flower diameter on the stem lineage of Rafflesiaceae, making this one of the most dramatic cases of size evolution reported for eukaryotes.
Return of the Giant Hogweed:
Mammoths With Hollow Feet
All photos © Kipling West
Hungry? Try some of Kipling's FRESH SPAM!
Classification of Geological Eras
In 1759, Italian geologist Giovanni Arduino (1714-1795) dated a letter to Professor A.Vallisneri the younger, in which Arduino proposed a classification of Earth's surface rocks according to four brackets of successively younger orders: Primary, Secondary, Tertiary and Quaternary. These are the four geological eras used today.
© Meyerowitz & Beard
The volcanic rocks without fossils which he saw in the Atesine Alps that formed the cores of large mountains he called Primary. Overlying them, the fossil rich rocks of limestone and clay that were found on the prealpine flanks of the mountains he called Secondary. The less consolidated fossil-bearing rocks of the subalpine foothills, he named Tertiary, and the alluvial rock deposits in the plains were the Quaternary. link.
Thursday, March 29, 2007
The Golden Age of Dino Discoveries
From BBC News:
Peter Dodson & Steve Wang created a computer model that came up with an astonishing prediction--it estimated that the museums and research institutes in the world only hold around 30% of the dinosaur fossils that may exist - the other 70% are still in the ground.
"Based on what has gone before, we projected into the future and found that at some point - we can't say when, but sometime in the next century or two, when we've found all the dinosaurs out there to find - the total number will be about 1,850 genres, or kinds, of dinosaur."
Estimating the diversity of dinosaurs. 2006. S. C. Wang and P. Dodson. PNAS 103 (37): 13601-13605.
Abstract: Despite current interest in estimating the diversity of fossil and extant groups, little effort has been devoted to estimating the diversity of dinosaurs. Here we estimate the diversity of nonavian dinosaurs at 1,850 genera, including those that remain to be discovered. With 527 genera currently described, at least 71% of dinosaur genera thus remain unknown. Although known diversity declined in the last stage of the Cretaceous, estimated diversity was steady, suggesting that dinosaurs as a whole were not in decline in the 10 million years before their ultimate extinction. We also show that known diversity is biased by the availability of fossiliferous rock outcrop. Finally, by using a logistic model, we predict that 75% of discoverable genera will be known within 60–100 years and 90% within 100–140 years. Because of nonrandom factors affecting the process of fossil discovery (which preclude the possibility of computing realistic confidence bounds), our estimate of diversity is likely to be a lower bound.
Peter Dodson & Steve Wang created a computer model that came up with an astonishing prediction--it estimated that the museums and research institutes in the world only hold around 30% of the dinosaur fossils that may exist - the other 70% are still in the ground.
"Based on what has gone before, we projected into the future and found that at some point - we can't say when, but sometime in the next century or two, when we've found all the dinosaurs out there to find - the total number will be about 1,850 genres, or kinds, of dinosaur."
Estimating the diversity of dinosaurs. 2006. S. C. Wang and P. Dodson. PNAS 103 (37): 13601-13605.
Abstract: Despite current interest in estimating the diversity of fossil and extant groups, little effort has been devoted to estimating the diversity of dinosaurs. Here we estimate the diversity of nonavian dinosaurs at 1,850 genera, including those that remain to be discovered. With 527 genera currently described, at least 71% of dinosaur genera thus remain unknown. Although known diversity declined in the last stage of the Cretaceous, estimated diversity was steady, suggesting that dinosaurs as a whole were not in decline in the 10 million years before their ultimate extinction. We also show that known diversity is biased by the availability of fossiliferous rock outcrop. Finally, by using a logistic model, we predict that 75% of discoverable genera will be known within 60–100 years and 90% within 100–140 years. Because of nonrandom factors affecting the process of fossil discovery (which preclude the possibility of computing realistic confidence bounds), our estimate of diversity is likely to be a lower bound.
Dead Dinos ≠ More Mammals
The delayed rise of present-day mammals. 2007. O. R. P. Bininda-Emonds, et al. Nature 446: 507-512.
Hey everyone, let’s put out a press release, and another one, and one more:
A new, complete 'tree of life' tracing the history of mammals on Earth shows that they did not diversify as a result of the death of the dinosaurs. It contradicts the previously accepted theory that the Mass Extinction Event that wiped out the dinosaurs 65 million years ago prompted the rapid rise of the mammals we see on the earth today.
Research shows that after the mass exteinxtion certain mammals did experience a rapid period of diversification and evolution. However, most of these groups have since either died out completely or declined in diversity.
The researchers believe that our 'ancestors', and those of all other mammals on earth now, began to radiate around the time of a sudden increase in the temperature of the planet – ten million years after the death of the dinosaurs.
Read the comment at Nature News.
FYI, the lead author is another fellow graduate (M.Sc., I think) from a few years back of the U of Calgary studying under Dr. A. P. Russell.
Hey everyone, let’s put out a press release, and another one, and one more:
A new, complete 'tree of life' tracing the history of mammals on Earth shows that they did not diversify as a result of the death of the dinosaurs. It contradicts the previously accepted theory that the Mass Extinction Event that wiped out the dinosaurs 65 million years ago prompted the rapid rise of the mammals we see on the earth today.
Research shows that after the mass exteinxtion certain mammals did experience a rapid period of diversification and evolution. However, most of these groups have since either died out completely or declined in diversity.
The researchers believe that our 'ancestors', and those of all other mammals on earth now, began to radiate around the time of a sudden increase in the temperature of the planet – ten million years after the death of the dinosaurs.
Read the comment at Nature News.
FYI, the lead author is another fellow graduate (M.Sc., I think) from a few years back of the U of Calgary studying under Dr. A. P. Russell.
The tendonitis has improved so I'll be slowing bring the blog back up to speed, although I'll probably not hit 100% of what I was doing before.
Wednesday, March 28, 2007
New Mongolian Raptors
From LiveScience.com: 
Fragments of a jawbone from the second raptor, Shanag ashile (above), was found in the Oosh region of Mongolia. It lived about 20 million years before Tsaagan and was probably much smaller, about the size of a small raven. Shanag likely resembled Microraptor, Turner said, a feathered bird-like dinosaur discovered in China that scientists think coasted between trees on two sets of wings.
A new dromaeosaurid theropod from Ukhaa Tolgod (Ömnögov, Mongolia). 2006. Mark A. Norell et al. American Museum Novitates.
Tsaagan mangas was unearthed in 1993 but only recently identified as a new raptor species. Credit: Mark NorellTsaagan mangas, was found in the Ukhaa Tolgod region of Mongolia. Tsaagan was slightly larger than a turkey and its skull is one of the best preserved dromaeosaurid skulls ever found.
A small derived theropod from Öösh, early Cretaceous, Baykhangor Mongolia 2007. Alan H. Turner, et al. American Museum Novitates.
Fragments of a jawbone from the second raptor, Shanag ashile (above), was found in the Oosh region of Mongolia. It lived about 20 million years before Tsaagan and was probably much smaller, about the size of a small raven. Shanag likely resembled Microraptor, Turner said, a feathered bird-like dinosaur discovered in China that scientists think coasted between trees on two sets of wings.
Tuesday, March 27, 2007
Monkey In The Mirror: Man's earliest ancestor had apelike face
Left: Dr. Richard Leakey’s reconstruction shows an erroneous vertical facial profile on a 1.9 million-year-old early human skull. Right: Bromage’s computer-simulated reconstruction shows the same skull with a distinctly protruding jaw. Green and red lines compare the location of the eyes, ears, and mouth, which must be in precise relationship to one another in all mammals. Credit: Dr. Timothy BromageFrom the press release:
A computer-generated reconstruction shows a 1.9 million-year-old skull belonging to Homo rudolfensis, the earliest member of the human genus, with a surprisingly small brain and distinctly protruding jaw, features commonly associated with more apelike members of the hominid family living as much as three million years ago.
Dr. Bromage's findings call into question the extent to which H. rudolfensis differed from earlier, more apelike hominid species. Specifically, he is the first scientist to produce a reconstruction of the skull that questions renowned paleontologist and archeologist Richard Leakey"s depiction of modern man"s earliest direct ancestor as having a vertical facial profile and a relatively large brain – an interpretation widely accepted until now.
Dr. Bromage's reconstruction also suggests that humans developed a larger brain and more vertical face with a less pronounced jaw and smaller teeth at least 300,000 years later than commonly believed, perhaps as recently as 1.6 million to one million years ago, when two later species, H. ergaster and H. erectus, lived. Dr. Bromage presented his findings today at the annual scientific session of the International Association for Dental Research in New Orleans.
'Ancestral eve' was mother of all tooth decay
Humans and their oral bacteria evolved from a common African ancestor
From the press release:
Researchers have found the first oral bacterial evidence supporting the dispersal of modern Homo sapiens out of Africa to Asia.
The team discovered that Streptoccocus mutans, a bacterium associated with dental caries, has evolved along with its human hosts in a clear line that can be traced back to a single common ancestor who lived in Africa between 100,000 and 200,000 years ago.
S. mutans is transmitted from mothers to infants, and first appears in an infant’s mouth at about two years of age. Caufield’s findings are reported in an article in the February issue of the Journal of Bacteriology.
In his analysis of the bacterium, Caufield used DNA fingerprints and other biomarkers that scientists have also employed to trace human evolution back to a single common African ancestor, known as "ancestral Eve."
Tuesday, March 20, 2007
Drum Riff
The APS conference on the weekend was a rousing success although the numbers were a bit down from last year. The U of A VP Gala on Sat. night was also a great success with a fistful of money raised for the paleo students. I had a chance to talk to a lot of the VP students and read through most of their posters—they’re a terrific bunch of frightfully bright students with some very cool projects on the go.
Kudos to Eric Snively for transporting me around on the weekend. I held a metaphorical shaken-up bottle of Diet Pepsi to his head and forced him to put together a press release for this very cool research recently published with Don Henderson. Hopefully it will be all over the media in a week or two!
Thanks to everyone who has written in support of the blog! I’m hoping for the best to be able to return to at least semi-regular postings in a week or so. If the camera continues to function well I’ll post more photos from the trip later in the week.
Sunday, March 18, 2007
Died This Day: Othniel Charles Marsh
From Today In Science History:
O.C. Marsh (October 29, 1931 - March 18, 1899)
In 1866, the Peabody Museum of Natural History was founded with a gift from George Peabody. The same year his nephew, O.C. Marsh, was also named its Professor of Paleontology, the first such appointment in the United States. In 1869 Marsh used the inheritance from his uncle to start to amass large collections of vertebrate fossils. He went on to long and successful career as a vertebrate paleontologist, most of which was spent fueding with is rival, E.D.Cope.
Marsh and Cope started their careers on a cordial basis, but the relationship soon soured over an incident involving Cope's fossil of Elasmosaurus. Embarassingly, Marsh pointed out that its backbones were mounted backwards. To settle the arguement the men agreed to let Joseph Leidy decide who was right. Leidy promptly removed the head from one end and placed it on what Cope had thought was the tail. Cope than frantically tried to collect all of the copies of a recently printed publication that contained his erroneous reconstruction.
O.C. Marsh (October 29, 1931 - March 18, 1899)
In 1866, the Peabody Museum of Natural History was founded with a gift from George Peabody. The same year his nephew, O.C. Marsh, was also named its Professor of Paleontology, the first such appointment in the United States. In 1869 Marsh used the inheritance from his uncle to start to amass large collections of vertebrate fossils. He went on to long and successful career as a vertebrate paleontologist, most of which was spent fueding with is rival, E.D.Cope.Marsh and Cope started their careers on a cordial basis, but the relationship soon soured over an incident involving Cope's fossil of Elasmosaurus. Embarassingly, Marsh pointed out that its backbones were mounted backwards. To settle the arguement the men agreed to let Joseph Leidy decide who was right. Leidy promptly removed the head from one end and placed it on what Cope had thought was the tail. Cope than frantically tried to collect all of the copies of a recently printed publication that contained his erroneous reconstruction.
Yes, a repost from 2005. On the plus side the tendonitis is getting better so I'm keeping my fingers crossed for posting again at a more regular pace once I'm back in Cleveland at the end of the month.
Tuesday, March 13, 2007
Happy Birthday Philip Currie
Photo of PJC in the Gobi © M. Ryan
FYI, if you’re in Edmonton this Saturday, the U of Alberta Laboratory for Vertebrate Palaeontology is holding their The 4th Annual Gala and Fundraiser 2007 for the museum and collections of vertebrate palaeontology at the Winspear Dining Room, Faculty Club; cocktails at 6:30 p.m. and dinner at 7:30 pm. Keynote speaker, Takuya Konishi, presents" Music of the Mosasaur" at 8:30 p.m. Silent Auction until 9:30 p.m. Tickets are $85.00 per person.
If you’re in Calgary this weekend the Alberta Palaeontological Society is hosting their annual conference; APS SYMPOSIUM 2007-DISCOVERING FOSSILS Saturday, March 17, 2007, from 9:15AM to 5:00PM - Alberta Palaeontological Society Eleventh Annual Symposium and workshops on Sunday March 18, 2007, 9:00 AM-4 PM (in conjunction with the Mount Royal College Earth Sciences and CSPG Palaeontological Division). More info HERE.
Sorry, I could not let these items go unnoted.
If you want to reach me drop me a line at:
Palaeoblog at yahoo dot ca
Palaeoblog at yahoo dot ca
Sunday, March 11, 2007
Not Fade Away
I mentioned a few weeks ago that postings on the blog would be slowing down due to my tendonitis. Since it’s not getting any better, and since I’ll be very busy over the next week and then away in Alberta for the APS conference and research after that, I’m putting the blog on hiatus until about the end of the month. At that point I’ll reevaluate my condition and see what I can do about resuming postings.
In the mean time if you’re a regular reader of the blog please consider dropping me a line and telling me where you’re from and why you read the blog—this will help me determine the future course of the blog. Due to my need to minimize typing I probably will not reply to you but I will read whatever you have to send my way.
I suspect that I’ll pop back for the occasional update and reposting, but for now I’m going to sign off and put on some ice packs.
Drop me a line at:
Palaeoblog at yahoo dot ca
Palaeoblog at yahoo dot ca
Died This Day: Roy Chapman Andrews
Roy Chapman Andrews (Jan.26, 1884-Mar.11, 1960)
American naturalist, explorer, and author, who spent his entire career at the American Museum of Natural History. He led many important scientific expeditions with financial support through his public lectures and books, particularly in central Asia and eastern Asia. On his 1925 central Asian expedition, the first known dinosaur eggs were discovered,as well as skull and parts of Baluchitherium, the largest known land mammal. During his career Andrews was the museum's best promoter, creating immense excitement and successfully advancing research there. link
Andrews was also acknowledged as one of the more important inspirations for the creation of the character of Indiana Jones.
American naturalist, explorer, and author, who spent his entire career at the American Museum of Natural History. He led many important scientific expeditions with financial support through his public lectures and books, particularly in central Asia and eastern Asia. On his 1925 central Asian expedition, the first known dinosaur eggs were discovered,as well as skull and parts of Baluchitherium, the largest known land mammal. During his career Andrews was the museum's best promoter, creating immense excitement and successfully advancing research there. linkAndrews was also acknowledged as one of the more important inspirations for the creation of the character of Indiana Jones.
Thursday, March 08, 2007
Vote For Jane
Jane at the CMNH. Photo: Liz Russell/CMNH
The Burpee Museum is in a state-wide contest to determine the "Seven Wonder's of Illinois". The winners are determined by on-line voting that is running now. So vote early and often (you can vote once a day) to help Mike and Scott put Jane on the map!
Go HERE to vote.
Sympatric Speciation of Finches
Ecological Speciation in South Atlantic Island Finches. 2007. P.G. Ryan et al. Science 315: 1420-1423.
Abstract: Examples of sympatric speciation in nature are rare and hotly debated. We describe the parallel speciation of finches on two small islands in the Tristan da Cunha archipelago in the South Atlantic Ocean. Nesospiza buntings are a classic example of a simple adaptive radiation, with two species
on each island: an abundant small-billed dietary generalist and a scarce large-billed specialist.
Their morphological diversity closely matches the available spectrum of seed sizes, and genetic evidence suggests that they evolved independently on each island.
Speciation is complete on the smaller island, where there is a single habitat with strongly bimodal seed size abundance, but is incomplete on the larger island, where a greater diversity of habitats has resulted in three lineages. Our study suggests that the buntings have undergone parallel ecological speciation. stamp
Abstract: Examples of sympatric speciation in nature are rare and hotly debated. We describe the parallel speciation of finches on two small islands in the Tristan da Cunha archipelago in the South Atlantic Ocean. Nesospiza buntings are a classic example of a simple adaptive radiation, with two species
on each island: an abundant small-billed dietary generalist and a scarce large-billed specialist.Their morphological diversity closely matches the available spectrum of seed sizes, and genetic evidence suggests that they evolved independently on each island.
Speciation is complete on the smaller island, where there is a single habitat with strongly bimodal seed size abundance, but is incomplete on the larger island, where a greater diversity of habitats has resulted in three lineages. Our study suggests that the buntings have undergone parallel ecological speciation. stamp
An unrooted allele network of mtDNA cytochrome b gene among Nesospiza shows that populations are separated by island rather than by traditional species boundaries. All branches are single mutations, unless otherwise specified alongside the branch. Sample sizes are shown adjacent to alleles.
Wednesday, March 07, 2007
Dinosaur Genome Deduced
Origin of avian genome size and structure in non-avian dinosaurs. 2007. C. L. Organ et al. Nature 446: 180-184.
Abstract: Avian genomes are small and streamlined compared with those of other amniotes by virtue of having fewer repetitive elements and less non-coding DNA. This condition has been suggested to represent a key adaptation for flight in birds, by reducing the metabolic costs associated with having large genome and cell sizes. However, the evolution of genome architecture in birds, or any other lineage, is difficult to study because genomic information is often absent for long-extinct relatives.
Here we use a novel bayesian comparative method to show that bone-cell size correlates well with genome size in extant vertebrates, and hence use this relationship to estimate the genome sizes of 31 species of extinct dinosaur, including several species of extinct birds.
Haploid genome size (mean of posterior predictive distribution) mapped onto a phylogeny shows a reduction within saurischian dinosaurs, the lineage to which birds belong.
Our results indicate that the small genomes typically associated with avian flight evolved in the saurischian dinosaur lineage between 230 and 250 million years ago, long before this lineage gave rise to the first birds.
By comparison, ornithischian dinosaurs are inferred to have had much larger genomes, which were probably typical for ancestral Dinosauria.
Bar graph of interspersed repetitive elements in a range of extant vertebrate species and extinct dinosaur species inferred from genome size reconstructions and the correlation between repetitive element composition and genome size.
Using comparative genomic data, we estimate that genome-wide interspersed mobile elements, a class of repetitive DNA, comprised 5–12% of the total genome size in the saurischian dinosaur lineage, but was 7–19% of total genome size in ornithischian dinosaurs, suggesting that repetitive elements became less active in the saurischian lineage.
These genomic characteristics should be added to the list of attributes previously considered avian but now thought to have arisen in non-avian dinosaurs, such as feathers, pulmonary innovations, and parental care and nesting.
Read the press release. More from Nature News.
Abstract: Avian genomes are small and streamlined compared with those of other amniotes by virtue of having fewer repetitive elements and less non-coding DNA. This condition has been suggested to represent a key adaptation for flight in birds, by reducing the metabolic costs associated with having large genome and cell sizes. However, the evolution of genome architecture in birds, or any other lineage, is difficult to study because genomic information is often absent for long-extinct relatives.
Here we use a novel bayesian comparative method to show that bone-cell size correlates well with genome size in extant vertebrates, and hence use this relationship to estimate the genome sizes of 31 species of extinct dinosaur, including several species of extinct birds.
Haploid genome size (mean of posterior predictive distribution) mapped onto a phylogeny shows a reduction within saurischian dinosaurs, the lineage to which birds belong.
Our results indicate that the small genomes typically associated with avian flight evolved in the saurischian dinosaur lineage between 230 and 250 million years ago, long before this lineage gave rise to the first birds.
By comparison, ornithischian dinosaurs are inferred to have had much larger genomes, which were probably typical for ancestral Dinosauria.
Bar graph of interspersed repetitive elements in a range of extant vertebrate species and extinct dinosaur species inferred from genome size reconstructions and the correlation between repetitive element composition and genome size.
Using comparative genomic data, we estimate that genome-wide interspersed mobile elements, a class of repetitive DNA, comprised 5–12% of the total genome size in the saurischian dinosaur lineage, but was 7–19% of total genome size in ornithischian dinosaurs, suggesting that repetitive elements became less active in the saurischian lineage.
These genomic characteristics should be added to the list of attributes previously considered avian but now thought to have arisen in non-avian dinosaurs, such as feathers, pulmonary innovations, and parental care and nesting.
Read the press release. More from Nature News.
Born This Day: The Chef Who Cooked The Primeval Soup
From Today in Science History:
Stanley Lloyd Miller (b.1930) is an American chemist who made a series of
famous experiments beginning in 1953, to determine the possible origin of life from inorganic chemicals on the primeval earth. He passed electrical discharges (simulating thunderstorms) through mixtures of reducing gases, such as hydrogen, ammonia, methane and water, 
that were believed to have formed the earliest atmosphere.
An analysis days later showed that the resulting chemicals included glycine and alanine, the simplest amino acids & the basic building blocks of proteins. Other compounds included urea, aldehydes and carboxylic acids. Thus, a "primeval soup" is the currently accepted most plausible explanation, though incomplete, of the origin of the complex organic molecules of life.
Stanley Lloyd Miller (b.1930) is an American chemist who made a series of
famous experiments beginning in 1953, to determine the possible origin of life from inorganic chemicals on the primeval earth. He passed electrical discharges (simulating thunderstorms) through mixtures of reducing gases, such as hydrogen, ammonia, methane and water, 
that were believed to have formed the earliest atmosphere. An analysis days later showed that the resulting chemicals included glycine and alanine, the simplest amino acids & the basic building blocks of proteins. Other compounds included urea, aldehydes and carboxylic acids. Thus, a "primeval soup" is the currently accepted most plausible explanation, though incomplete, of the origin of the complex organic molecules of life.
Tuesday, March 06, 2007
Submitted This Day: Structure of DNA
image
From Today In Science History:
Today in 1953, Watson and Crick submitted to the journal Nature their first article on the structure of DNA, ”Molecular Structure of Nucleic Acids: A structure for deoxyribose nucleic acid”, which was published on April 25.
"We wish to put forward a radically different structure for the salt of deoxyribose nucleic acid. This structure has two helical chains each coiled around the same axis... Both chains follow right-handed helices... The novel feature of the structure is the manner in which the two chains are held together by purine and pyrimidine bases... They are joined together in pairs, a single base from one chain being hydrogen-bonded to a single base from the other chain, so that the two lie side by side with identical z-co-ordinates. One of the pair must be a purine and the other a pyrimidine in order for bonding to occur."DNA replication:
Via NeatoRama
Sunday, March 04, 2007
Mark Schultz Art Books
© Mark Schultz
© Mark Schultz
Both Various Drawings, Volume 1 and Volume 2 are in short supply (Vol.1 might even be sold out now).
Limb Posture in Early Mammals
Limb posture in early mammals: Sprawling or parasagittal. 2007. Zofia Kielan-Jaworowska and Jørn H. Hurum. Acta Palaeontologica Polonica 51: 2006: 393-406
Abstract [edit]: The limb posture in early mammals is a matter of controversy. Kielan-Jaworowska and Gambaryan presented arguments for a sprawling posture in multituberculates, based mainly on three characters of the hind limbs (deep pelvis, mediolateral diameter of the tibia larger than the craniocaudal, and position of MtV, which fits the peroneal groove on the calcaneus and is not aligned with the axis of tuber calcanei). Here we present two more arguments for sprawling hind limbs in early mammals.
1: the presence of an os calcaris, supporting the probably venomous spur in hind legs of docodontans, multituberculates, eutriconodontans, and “symmetrodontans”, similar to those of extant monotremes. We argue that early mammals (except for boreosphenidans) had sprawling limb posture and venomous spur; acquisition of the parasagittal stance was apparently characteristic only of boreosphenidans, in which the spur has not been found.
2: based on taphonomic evidence from lacustrine conditions (e.g., Early Cretaceous Jehol Biota), in which the mammalian skeletons, except for boreosphenidans (Sinodelphys and Eomaia), have been preserved compressed dorso-ventrally, suggesting sprawling stance.
Download the PDF HERE.
Read about Jørn’s last appearance on the palaeoblog HERE
Abstract [edit]: The limb posture in early mammals is a matter of controversy. Kielan-Jaworowska and Gambaryan presented arguments for a sprawling posture in multituberculates, based mainly on three characters of the hind limbs (deep pelvis, mediolateral diameter of the tibia larger than the craniocaudal, and position of MtV, which fits the peroneal groove on the calcaneus and is not aligned with the axis of tuber calcanei). Here we present two more arguments for sprawling hind limbs in early mammals.
1: the presence of an os calcaris, supporting the probably venomous spur in hind legs of docodontans, multituberculates, eutriconodontans, and “symmetrodontans”, similar to those of extant monotremes. We argue that early mammals (except for boreosphenidans) had sprawling limb posture and venomous spur; acquisition of the parasagittal stance was apparently characteristic only of boreosphenidans, in which the spur has not been found.
2: based on taphonomic evidence from lacustrine conditions (e.g., Early Cretaceous Jehol Biota), in which the mammalian skeletons, except for boreosphenidans (Sinodelphys and Eomaia), have been preserved compressed dorso-ventrally, suggesting sprawling stance.
Download the PDF HERE.
Read about Jørn’s last appearance on the palaeoblog HERE
T. rex Wins By A Nose
Fused and vaulted nasals of tyrannosaurid dinosaurs: Implications for cranial strength and feeding mechanics. 2007. Eric Snively, Donald M. Henderson, and Doug S. Phillips. Acta Palaeontologica Polonica 51: 2006: 435-454.
Abstract: Tyrannosaurid theropods display several unusual adaptations of the skulls and teeth. Their nasals are fused and vaulted, suggesting that these elements braced the cranium against high feeding forces. Exceptionally high strengths of maxillary teeth in Tyrannosaurus rex indicate that it could exert relatively greater feeding forces than other tyrannosaurids. Areas and second moments of area of the nasals, calculated from CT cross-sections, show higher nasal strengths for large tyrannosaurids than for Allosaurus fragilis.
Cross-sectional geometry of theropod crania reveals high second moments of area in tyrannosaurids, with resulting high strengths in bending and torsion, when compared with the crania of similarly sized theropods. In tyrannosaurids trends of strength increase are positively allomeric and have similar allometric exponents, indicating correlated progression towards unusually high strengths of the feeding apparatus. Fused, arched nasals and broad crania of tyrannosaurids are consistent with deep bites that impacted bone and powerful lateral movements of the head for dismembering prey.
You can download a PDF of the article HERE
Eric’s a fellow member of the Southern Alberta Dinosaur Research Group and great person to have in the field.
I can't remember if we congratulated Don Henderson who became the new Head of Dinosaur Research at the Royal Tyrrell Museum last summer--if not, a belated tip of the hat!
Abstract: Tyrannosaurid theropods display several unusual adaptations of the skulls and teeth. Their nasals are fused and vaulted, suggesting that these elements braced the cranium against high feeding forces. Exceptionally high strengths of maxillary teeth in Tyrannosaurus rex indicate that it could exert relatively greater feeding forces than other tyrannosaurids. Areas and second moments of area of the nasals, calculated from CT cross-sections, show higher nasal strengths for large tyrannosaurids than for Allosaurus fragilis.
Cross-sectional geometry of theropod crania reveals high second moments of area in tyrannosaurids, with resulting high strengths in bending and torsion, when compared with the crania of similarly sized theropods. In tyrannosaurids trends of strength increase are positively allomeric and have similar allometric exponents, indicating correlated progression towards unusually high strengths of the feeding apparatus. Fused, arched nasals and broad crania of tyrannosaurids are consistent with deep bites that impacted bone and powerful lateral movements of the head for dismembering prey.
You can download a PDF of the article HERE
Eric’s a fellow member of the Southern Alberta Dinosaur Research Group and great person to have in the field.
I can't remember if we congratulated Don Henderson who became the new Head of Dinosaur Research at the Royal Tyrrell Museum last summer--if not, a belated tip of the hat!
Saturday, March 03, 2007
Albertaceratops, New Horned Dino
A New Basal Centrosaurine Ceratopsid From the Oldman Formation, SE Alberta. 2007. J. Paleo. 81: 376-396.
Press release and more images over at the Southern Alberta Dinosaur Research Group site.
Visit Mike Skrepnick’s web site: Dinosaurs in Art.
© 2007 Michael Skrepnick.
Abstract: A new centrosaurine ceratopsid, Albertaceratops nesmoi, is described from the lower Oldman Formation (Upper Cretaceous) of southern Alberta, and is based on a single, almost complete skull. Referred material is described from equivalent beds in the Judith River Formation of north-central Montana. A limited phylogenetic analysis of the Ceratopsidae places the new taxon as the basal member of the Centrosaurinae and indicates that robust, elongate postorbital horncores that form a synapomorphy of (Ceratopsidae + Zuniceratops) are also present in Centrosaurinae.Press release and more images over at the Southern Alberta Dinosaur Research Group site.
Visit Mike Skrepnick’s web site: Dinosaurs in Art.
Friday, March 02, 2007
Ossified Tendon Trellis in Chasmosaurus
An ossified tendon trellis in Chasmosaurus (Ornithischia:Ceratopsidae). 2007. R. Holmes and C. Organ. J. Paleo. 81: 411-414.
A nice note by my old CMN colleague, Rob Holmes, and Chris Organ on a feature not previously reported for ceratopsians.
The critter is C. irvinensis. You can see a nice animation of the animal pulling itself out of its rocky matrix and walking away HERE. The video is from the display at the CMN in Ottawa.
A nice note by my old CMN colleague, Rob Holmes, and Chris Organ on a feature not previously reported for ceratopsians.
The critter is C. irvinensis. You can see a nice animation of the animal pulling itself out of its rocky matrix and walking away HERE. The video is from the display at the CMN in Ottawa.
New Shark Species Discovered
From National Geographic News:
At least 20 previously unknown species of sharks and rays have been found during a survey of local fish markets in Indonesia, scientists say. The five-year study focused on catches from tropical seas around the Southeast Asian country, which encompasses more than 17,000 islands.
So far six of the new species have been described in scientific journals. These include the Bali catshark, the Jimbaran shovelnose ray, and the Hortle's whipray.
Read the full story HERE.
Thursday, March 01, 2007
Monophyletic Halwaxiids From The Burgess Shale
Halwaxiids and the Early Evolution of the Lophotrochozoans. 2007. S.C. Morris and J.-B. Caron. Sciene 315: 1255-1258.
Abstract: Halkieriids and wiwaxiids are cosmopolitan sclerite-bearing metazoans from the Lower and Middle Cambrian. Although they have similar scleritomes, their phylogenetic position is contested. A new scleritomous fossil from the Burgess Shale has the prominent anterior shell of the halkieriids but also bears wiwaxiid-like sclerites. This new fossil defines the monophyletic halwaxiids and indicates that they have a key place in early lophotrochozoan history.
Abstract: Halkieriids and wiwaxiids are cosmopolitan sclerite-bearing metazoans from the Lower and Middle Cambrian. Although they have similar scleritomes, their phylogenetic position is contested. A new scleritomous fossil from the Burgess Shale has the prominent anterior shell of the halkieriids but also bears wiwaxiid-like sclerites. This new fossil defines the monophyletic halwaxiids and indicates that they have a key place in early lophotrochozoan history.
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The Word Made Cardboard
Where religon and technology meet: