The discovery of feathered dinosaurs led to our understanding that birds are the descendents of dinosaurs, specifically the group of dinosaurs that includes the sauropods, like Apatosaurus and the theropods like Tyrannosaurus.
However, the discovery of feather-like structures in a small dinosaur from the other major dinosaur lineage—the group that includes Triceratops and Steogsaurus—complicates things.
Tianyulong is a small herbivorous dinosaur from China with feather-like structures along its spine and tail. Paleontologists are not yet sure whether these are feathers as seen in other feathered dinosaurs, or some other sort of body covering evolutionarily unrelated to true feathers.
Scientists refer to the structures on Tianyulong as “dinofuzz”, a fitting term because this new fossil fuzzes up our picture of dinosaur-bird relationships, at least for now.
Source: Xio-ting Zheng, et al., 2009, An Early Cretaceous heterodontosaurid dinosaur with filamentous integumentary structures. Nature 458:333-336.
330 million years ago, during the Carboniferous Period, a marine-dwelling arthropod hoisted itself out of the water and dragged its tail-like telson across the wet mud.
The record of this early excursion is a 6-meter-long trackway preserved in sandstone from Scotland. The trackway is attributed to a euyrpterid or “sea scorpion” whose fossil remains are known from the area.
The trackway consists of two parallel rows of footprints and a continuous groove in the middle marking the telson dragmark. The width of the trackway, indicates that the animal was 1 meter wide, and perhaps 2 meters long. The telson drag mark suggests that the animal was moving out of water, because underwater the eurypterid would not have dragged its telson.
The trackway confirms suspicions that some eurypterid could leave their aquatic habitat and venture onto land. These footprints also have the distinction of being the largest known tracks of an invertebrate.
http://news.bbc.co.uk/2/hi/uk_news/scotland/edinburgh_and_east/8632427.stm
The tongue-twister about woodchucks could be asked of Castoroides ohioensis, the so-called giant beaver that inhabited North America during the last ice age, about 14,000 years ago.
The ice age animal was about twice the size of modern beavers, but, surprisingly, there is no evidence that the ice age beaver ate wood.
We are what we eat, and researchers from Michigan State University and the University of Wisconsin studied the isotopic composition of a jawbone of the ice age beaver and found that the ratio of carbon 13 to carbon 12 did not match that expected for an animal that ingested wood, but was closer to that of an animals that dined on aquatic plants.
The scientists compared the giant beaver to be, ecologically, “like little hippos.”
Source: Catherine Yansa, Geological Society of America Meeting, October 19, 2010
Geological Society of America Abstracts with Programs, Vol. 41, No. 7, p. 257
Reported by Perkins, S., Science News, November 21, 2009
Illustration (inset): giant beaver compared to modern beaver. From www.nature.ca
Ichythosaurs, the dolphin-shaped, marine-dwelling reptiles of the Mesozoic Era, shared the Mesozoic seas with other reptile predators, like mosasaurs and plesiosaurs, but the discovery of a 10-meter long ichthyosaur from 240 million year old rocks in Nevada lays claim to top carnivore in Early Mesozoic marine ecosystems.
The Nevada ichythosaur has serrated teeth, previously unknown in ichythosaurs from this age. Other ichythosaurs of this time had conical teeth fit for grabbing fish and swallowing them whole, or blunt teeth suited for crushing shelly invertebrates like ammonites.
Later ichthyosaurs had serrated teeth, but did not reach the size of the Nevada specimen. This new find indicates that ichythosaurs were ecologically more diverse early in their evolutionary history than previously suspected.
Source: Nadia Frobisch, September 23, 2010, Society of Vertebrate Paleontology meeting.
Illustration from : http://www.marshalls-art.com/images/ipaleo/paleopg17/Ichthyosaurs_final.jpg
Modern medical technology has made it possible to study old anatomies.
Computerized tomography, or CT scanning can be used on fossils to study their internal structure. CT scans of the brain case of an Archaeopteryx skull shows that this transitional form between reptiles and birds had a brain region associated with vision that made up almost 1/3 of the brain’s volume.
The lobes associated with hearing and muscle coordination were also well-developed. The ratio of brain volume to body mass is higher than that associated with modern reptiles but a bit less than that for modern birds, more evidence for the intermediate position Archaeopteryx occupies between birds and reptiles.
CT scans also showed that the structure of the inner ear of Archaeopteryx more closely resembles tat of modern birds than reptiles.
In sum, it appears that Archaeopteryx had well developed senses of hearing, balance, and sight, traits that support the hypothesis that Archaeopteryx was capable of flight.
The photo is from http://digimorph.org/specimens/Archaeopteryx_lithographica/ check it out to rotate it and examine the skull from other angles.
Sources:
Science News Aug. 7, 2004, p. 166
Timothy B. Rowe, Nature, August 5, 2004
A 121-million-year-old fossilized bird embryo from China provides evidence that at some ancient chicks were able to care for themselves after hatching.
The China fossil bird is well-ossified, with nearly complete feathers and a large skull, indicating that the hatchling was able to walk and feed independently upon hatching.
Younger fossil bird embryos from 75 million-year old rocks in Argentina do not have feathers preserved. The difference between the China and Argentina embryos might indicate an evolutionary trend in hatchlings, from precocial to altricial in that 45 million year time span, or it may reflect preservation differences; Argentina embryos may have been at an earlier stage of development or had feathers that were not preserved.
It will take a few more discoveries of well-preserved fossil hatchlings to confirm the hypothesis.
Sources:
Science News 23 Oct. 2004, p. 166
Science Oct. 22, 2004 Zhonge Zhou and f.Zhang
Scientists went prospecting along Alaska’s Yukon River, not for gold, but for soil samples in the permafrost looking for DNA from the urine and feces of ice-age mammals.
They struck it rich, and identified DNA from mammoth, bison, moose, horse, and snow shoe hare. The mammoth and horse DNA came from sedimentary layers about 10,000 years old—that is more recent than the youngest known fossil bones of these animals by at least 300 years.
The permafrost DNA implies that these species survived longer than originally presumed on the basis of the skeletal fossil remains, and indicates that the ice-age extinction of large mammals in North America was not a sudden event as previously thought.
Photo credit and more info: http://www.physorg.com/news180095166.html
Along with collecting modern plants and animals during his sojourn on the Beagle, Charles Darwin collected fossils.
He is credited with being the first scientist to examine fossils in the Falkland Islands, where he collected fossil brachiopods, but he is better remembered for the large bones of extinct fossil mammals that he found on his excursions in Patagonia, mastodon, giant ground sloths called Megatheria, and the armadillo-like Glyptodon, and fossil horses, which previously were unknown in the Americas.
Image: reconstructions by Richard Owen based on fossils collected by Charles Darwin.
The oldest known fossil beetle has been discovered not in an outcrop, but in a museum drawer. A 296 million year old insect has been reclassified as a beetle, pushing back the origin of beetles by millions of years.
The evolutionary success of beetles is traditionally explained by their two-stage life style—they pass through ecologically distinct larval and adult stages that allow them to exploit different niches.
However, the new find creates a large gap between the first appearance of beetles and the diversification of beetles that occurred 65 million years later, and suggests that the innovation of the two-stage lifestyle was not the initial cause of beetle diversity.
This opens the door to other explanations for beetle success, such as the proliferation of the plant species that was favored by the beetle larvae.
Reference: Journal of Paleontology November, 2009, The Earliest Beetle identified (Olivier Bethoux)
Photo credit: This is a much younger fossil beetle from the Eocene (15 million-year-old) Florissant Fossil Beds of Colorado, which preserves a wide variety plant and animal life. Click on today's title for more information.
Headlines in paleontology usually center on the oldest or first find of a fossil species. However, determining the youngest or last occurrence of a now-extinct species is just as important.
A youngest occurrence was recently confirmed for an extinct group of echinoderms, the phylum that includes starfish, sand dollars, and brittle stars.
Edrioasteroids are one of a number of bizarre echinoderms that went extinct by the end of the Paleozoic Era for reasons not yet understood. These silver-dollar sized, disc-shaped animals lived attached to shells or other hard surfaces on the sea floor.
This discovery comes as paleontologists focus their energy on looking for these fossils in younger rocks to answer questions about the reason for their demise.
Photo credit: drydredgers.org
For more pictures of edrioasteroids click on today's title.
Reference:
All the previously described lagerstatte are deposits of organisms from a marine environment. The fifth and final pick for "greatest fauna" is something completely different: The fossils encased in the La Brea tarpits were land-dwellers who became entrapped in a natural asphalt spring, and if for no other reason, the unique environment and fossilizing agent earn the La Brea tarpits a place on our list of top 5 fossil faunas.
How can an animal be so stupid as to fall into an asphalt pool? These were probably not steaming or bubbling pits like the mudpots and geysers of Yellowstone, but still pools of dense oil muck camoflaged by plant debris and perhaps even holding a pool of water.
Animals that came to take a drink got stuck, their distress cries were heard by predators who themselves became ensnared, and finally scavengers that came along for the easy pickings became mired in the muck—leaving a record of the whole food chain, from plants to insects to mammoths to saber tooth tigers and vultures—650 species of plants and animals so far identified, on the basis of 3.5 million fossils recovered, an astonishing diversity of animals that gives us an unprecedented window into an ice-age ecosystem.
Photo from www.papermag.com/blogs/2008/11/mr_mickeys_mustsee_guide_to_la_1.php
This famous lagerstatte from southern Germany is an obvious choice for a “greatest fossil fauna” list because it is in these fine-grained limestones representing the deposits of an ancient lagoon that the fossils of Archaeopteryx were found.
Archaeopteryx was the first evidence for a link between birds and reptiles, and the discovery of the first specimen came only a few months after Charles Darwin published Origin of Species, in which he made the case for a common ancestry for all organisms.
One of Darwin’s most vexing problems was the apparent lack of the transitional forms between major groups that his theory predicted, and the discovery of Archaeopteryx was an answer to this dilemma.
The lagoon that preserved Archaeopteryx down to its feathers also preserved insects, crustaceans, and echinoderms in exquisite detail, and give us a glimpse into a 150-million-year-old nearshore ecosystem.
The Gunflint chert is part of a sequence of 1.8 billion-year-old rocks exposed in the Gunflint Range of northern Minnesota and western Ontario along the north shore of Lake Superior.
These rocks contain stromatolites, organo-sedimentary structures formed by cyanobacteria trapping and binding sediment, and when examined under the microscope, small spheres, rods and filaments less than 10 micrometers in size are visible in the chert layers--microfossils preserved in near-pristine 3-D.
The discovery of the Gunflint chert caused a paradigm shift in paleontology, as it proved that under exceptional conditions, even very ancient lifeforms could be preserved.
For its role in opening our eyes to the presence of life in very ancient rocks, the Gunflint chert earns a place on our list of “top 5 fossil lagerstatte”
Photo credit: http://www.fas.org/irp/imint/docs/rst/Sect20/A12.html
This chapter is a preemptive strike against anticipated criticisms of Darwin’s ideas.
One obvious potential flaw in Darwin’s theory of common descent was the apparent lack of transitional forms linking different groups in the fossil record. Darwin himself asked, “Firstly, why, if species have descended from other species by insensibly fine gradations, do we not everywhere see innumerable transitional forms?” Darwin’s response to this question was to invoke the imperfection of the geological record, the fact that fossilization is the exception rather than the rule. Darwin wrote, “The crust of the earth is a vast museum, and the natural collections have been made only at intervals of time immensely remote.”
Darwin’s theory of gradual change made the prediction that transitional forms should exist, and this prediction has been borne out many times in the 150 years since publication of the “Origin” by new fossil discoveries.
Image: Archaeopteryx, whose discovery just after publication of the Origin lent support to Darwin's theory.
The recent apparent hoax by a Colorado couple seeking fame and fortune by preying on the credulity of the general public and abetted by their considerable skills as trained actors is the inspiration for this week’s blog. Hoaxes succeed where access to information in a situation is controlled by the party perpetrating the hoax, and fields of study that rely on unique, one-of-a kind observations or objects are more susceptible to hoaxes. Think art forgeries or in paleontology, unique fossils purported to be missing links. In the history of paleontology several episodes stand out, they range in time from the 1800s to the 1990s, but the reasons for the hoaxes are essentially the same as the recent one in the news because this aspect of human nature hasn’t changed. PT Barnum is supposed to have said, " There’s a sucker born every minute"*; the writer of the book of Ecclesiastes put it more eloquently as, “there is nothing new under the sun.”
*And PT Barnum is in fact associated with a paleontological/anthropological hoax, the Cardiff Giant (shown here). See www.roadsideamerica.com/ story/2172
