Thread: Fossil Finds
July 28th 2009, 09:10 AM #361
Re: Fossil Finds
Would you say this hints that universal common descent may not be entirely correct?
July 28th 2009, 10:35 AM #362
July 28th 2009, 10:58 AM #363
July 28th 2009, 11:04 AM #364
July 28th 2009, 11:40 AM #365
Re: Fossil Finds
K. I'm a self-admitted noob when it comes to these matters. I apologize if I ask dumb questions.
July 28th 2009, 11:43 AM #366
July 28th 2009, 08:04 PM #367
Re: Fossil Finds
Yeah, this really has nothing to do with common descent, whether from the LUCA ("Last Universal Common Ancestor," that is, some population of singled-celled lifeforms from which all the life on the planet, fossil or current, descended) or from the common ancestor of multidelled animal life...
The LUCA may have lived as long as 3.7+ billion years ago, and these latest findings have nothing to do with that early event.
That the fossils of the first multi-celled animals, who may have arisen sometime between a billion years ago and around 600 million years ago, are now being found in lacustrine (lakebed) rather than marine environments, is interesting and opens the way for further research, but also has little to do with common ancestry, as such.
The Doushanto is what is known as a laggerstetten province -- a locale where conditions of exceptional preservation have opened a window into the life of a past era with unprecedented detail. This is partly due to the minerals and chemistry involved, and partly to due with the very fine particles of the sediment which incapsulated these very small and delicate specimens -- in some cases preserving embryos within a few cell divisions of the original fertilized egg.
Such sites will always be exceedingly rare, by the very nature of things. While the possible environments to look for traces of the earliest animal life have now been broadened, it certainly remains possible that an even earlier marine environment could still have preserved fossils at the necessary level of size and detail, but just hasn't been found yet.
Or it may turn out that multi-celled animal life did, for some reason, actually begin in lake environemnts (for example, due to the oxygen availability hypothesis which is floated in the articles).
But that wouldn't change the fact that multi-celled animals are descended from earlier eukaryotes, or that eukaryotes represent a merger or symbiosis of still earlier types of one-celled critters, who were in turn ultimately descended from the LUCA...
As rogue has noted, the genetic evidence (an independent line of evidence from the fossil evidence) is overwhelming in establishing the general outlines of common descent leading to metazoans (LUCA ==> single-celled critters ==> eukaryotes ==> multi-celled animals...).
July 29th 2009, 04:42 PM #368
Re: Fossil Finds
Researchers have identified the first arboreal, or tree-climbing, vertebrate that lived some 30 million years before the first dinosaurs and were ancestors of mammals. More than 15 near-complete and well-preserved fossilized skeletons of the creature were excavated from a 260 myo (Late Permian) block of mudstone from central Russia's Kirov region.
Specimens included both mature individuals and some of youngsters, which should prove invaluable in providing a complete picture of the creature's skeletal anatomy as it aged. Researchers say they have an example of virtually every bone. The fact that so many were found together suggests that they were social animals.
The creature was named Suminia getmanovi and measured about 20” (50.8cm) from its nose to the tip of its prehensile tail. Suminia was long-limbed with elongated digits (their hands and feet accounted for approximately 40% of the limb), long curved claws and an opposable thumb – all useful characteristics for living high up in the trees. Abrasion marks on its large, distinctive teeth indicate that it fed on rough, fibrous plants.
The discovery is notable in that it furnishes the first fossil evidence of the partitioning of food resources between small climbing and large ground-dwelling herbivores. The arboreal existence of Suminia kept it safe from ground-dwelling predators as well as provided them with access to new sources of food.
This event that took place shortly after the establishment of the terrestrial ecosystem that we’re familiar with – a large number of herbivores supporting a much smaller number of carnivores.
Prior to that, according to Dr. Jörg Fröbisch a paleontologist at the Field Museum in Chicago, and team leader, “terrestrial vertebrate communities were composed of various-sized predators and relatively few plant-eaters, with most of the food resources being provided by insects and aquatic organisms."
Suminia belonged to the class of animal known as the Synapsida, which were a relatively common and varied group of mammal-like reptiles from the Permian and Triassic that gave rise to modern mammals.
Synapsids all originally possessed a single hole in each side of their skulls behind the eye socket to allow more room for the jaw muscles. Reptiles (including dinosaurs) and birds are diapsids, which all originally had two holes in each side of their skull.
"Non-mammalian synapsids were formerly unofficially known as 'mammal-like reptiles,' but they are actually not at all reptiles, but are more closely related to mammals," Fröbisch stated, adding that Suminia undeniably "is a distant relative of mammals."
A few fragments of Suminia were found back in 1994, and while enough for it to be named and briefly described, they were far too incomplete to provide much information about its appearance and behavior.
Fröbisch and his colleagues published their research findings in the science journal Proceedings of the Royal Society B.
The Late Permian herbivore Suminia and the early evolution of arboreality in terrestrial vertebrate ecosystems Abstract
Before Dinosaurs, the First Tree-Climber Revealed
Mammals’ family tree predates the dinosaurs
First Vertebrate To Live In Trees Described
Field Museum researchers identify 1st tree-dwellersAlways strive to keep an open mind – but not so open that your brains fall out!Still afeared of & dodging The PINTM
July 30th 2009, 11:55 AM #369
Re: Fossil Finds
Was “Lucy” and her kin meat-eaters? New research which examined the vertebrae from an Australopithecus africanus that was excavated from Sterkfontein in South Africa and is roughly 2.4 to 2.8 myo indicates that the answer is ‘yes.’
The researchers, led by Ruggero D'Anastasio with the Department of Human Movement Sciences, Section of Anthropology at the Faculty of Sciences of Motorial Education of the State University “G. d’Annunzio” in Chieti, Italy, detected lesions on the 4th and 5th lumbar vertebrae that was consistent with all the skeletal characteristics of the initial phases of brucellosis.
Brucellosis, commonly called “Mediterranean (or “Malta”) fever,” is a contagious disease and is typically caused by the consumption of meat from an infected animal and causes fever, sweating and muscle and joint pain which usually last for 3 to 6 months.
The fact that it is possible to get brucellosis from unsterilized dairy products as well means that the presence of the disease doesn’t automatically guarantee that the victim ate meat, but it seems extremely unlikely that Australopithecus was domesticating animals for their milk.
The team submits that this is the oldest evidence (though indirect) that Australopithecus included meat in their diet although cut marks on animal remains and stone tools that could have caused these marks dating from 2.5 mya have been found previously.
As D'Anastasio and his colleagues noted, carnivorous behavior has been observed in chimpanzees and baboons so it seems very likely that our predecessors might have consumed meat as well.
Many experts think that the consumption of meat played an important role in the supporting, directing or altering of human evolution, although it hasn’t been determined exactly when our ancestors began consuming enough of it to have an effect.
Possible Brucellosis in an Early Hominin Skeleton from Sterkfontein, South Africa Abstract & Paper
Possible Brucellosis in an Early Hominin Skeleton from Sterkfontein, South Africa – PLoS ONE
Tip 'o hat to SteveF at TalkRationalAlways strive to keep an open mind – but not so open that your brains fall out!Still afeared of & dodging The PINTM
August 5th 2009, 05:24 PM #370
Re: Fossil Finds
An analysis of an exceptionally well-preserved remains of a duck-sized adult pterosaur unearthed in shale sediments dating from 140 to 130 mya (Late Jurassic to Early Cretaceous) and found in the world famous Daohugou fossils beds of Inner Mongolia, China has revealed several significant facts about the long extinct flying reptiles.
The 30cm (nearly 1’) long pterosaur itself was named Jeholopterus ninchengensis and had a head that was longer than it was wide with a broad mouth full of peg-like teeth which led the team to suggest it probably was an insectivore. But none of this is what made the find particularly interesting.
The first was revealed when a new technique involving the shining of ultra-violet rays on the specimen showed that the preserved membrane that made up Jeholopterus’ wing consisted of at least three layers of fibers unlike anything found on any living creature and suggests that it had better control of its flight than previously thought. IOW, the picture of pterosaurs (or at least this type) as being merely gliders has to be scraped.
As the lead author of the paper describing the findings, Alexander Kellner, a paleontologist at the Museu Nacional (National Museum) in Rio de Janeiro, noted, the fibers "would have made it easier to make subtle adjustments of the wing membrane when flying, perhaps giving them better flight capability,"
Previously it was thought the membranes of pterosaur wings consisted of a single layer of densely packed structural fibers called actinofibrils that appear to be a feature exclusive to them. It has been thought that these fibers primarily served to reinforce the wing and prevent tears. Considering that the fibers in the layers are laid down in a crisscrossing pattern (each layer oriented in a different direction) like plywood, this seems to be a logical conclusion.
The team thinks if we can determine exactly what a pterosaur’s actinofibrils were made of it would provide an insight into the fibers' actual purpose: "Were they muscle? Collagen? Keratin? Stiff? Elastic?" Kellner asked.
The wing itself was probably attached at the ankle with Jeholopterus itself having a roughly 90cm (just under 3’) wingspan.
The second thing they discovered was that Jeholopterus’ has thick hair-like fibers all over its body and part of its wings that are structurally unlike the hair seen on any other animal. The team thinks they may have helped to control body-temperature and indicates that they were warm-blooded.
These hairs had previously been thought to have likely been proto-feathers. And earlier when similar fibers had been found on pterosaurs researchers had speculated about whether they were simply products of tissue decay.
The third and final thing the researchers discovered in their examination of Jeholopterus was that there was a long “horny covering” sheathing the pterosaur’s claws which signify that the claws were much longer in life than previously thought.
"This corroborates with the hypothesis that these animals were good climbers and could have been living in trees," Kellner said.
The discovery that Jeholopterus was probably a warm-blooded insect eater that probably spent time in trees and possessed more sophisticated flying skills than was realized may not hold true for other pterosaurs which ranged in size from small to the largest creatures to have ever flown.
The paper is due to be published in the current Proceedings of the Royal Society B.
Pterosaur Features Defy Comparison
Pterosaur's Wing, "Hairs" Unlike Any Living Animals'
Ancient pterosaurs were skilled fliersAlways strive to keep an open mind – but not so open that your brains fall out!Still afeared of & dodging The PINTM
August 5th 2009, 10:56 PM #371
Re: Fossil Finds
August 6th 2009, 05:01 PM #372
Re: Fossil Finds
I knew something more was probably involved than just "a wing and a prayer."
August 11th 2009, 04:50 PM #373
Re: Fossil Finds
Rogue hasn't announced a new fossil find in five days...
Creationists everywhere are cautiously optiminstic. Jorge has been sighted looking up from playing with his smiley collection. The DiscoTute is planning an announcement.
On all of their minds -- the potential imminent demise of Darwinism.
Will an entire WEEK go by without a significant new fossil find? Will the hopes of the creationists be realized? Will the ToE go down in flames, the fossil record finally played out?
Will Ken leave Sally and return to Gina?
Stay tuned for another exciting episode of "Name That Fossil!"
August 11th 2009, 11:17 PM #374
August 12th 2009, 12:39 AM #375
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