A trail of fossil footprints discovered in central Poland are the earliest known evidence of dinosaur traits to appear in the early Mesozoic era. Made by a small, cat-sized creature that walked on all fours, the tracks date back to just one to two millions after the mass extinction that marked the end of the Permian period and the beginning of the Triassic period 252 million years ago. The footprints contain several traits linking it to dinosaurs, including feet with reduced first and fifth toes; prominent and evenly aligned middle toes; and straight and simply hinged ankle configurations. Led by Steve Bussette from the American Museum of Natural History, the research appears in Proceedings of the Royal Society B
Although not quite yet dinosaurs per se, the creatures that made the tracks were more closely related to them than they were to other archosaurs such as pterosaurs and crocodiles. It's not clear how the archosaurs survived the Permian extinction since most sea creatures and more than 70 per cent of terrestrial species were wiped off the face of the Earth. But whatever the case, dinosaurian traits evolved soon after the "Great Dying", and rose up in a landscape primed for the Age of Dinosaurs.
Courtesy Nicole MillerA dinosaur tracksite discovered recently in the southwestern United States contains so many footprints it’s being heralded as a “dinosaur dance floor”.
Winston Seiler, a geologist at the University of Utah published a paper in the October 2008 issue of the journal Palaios that details the new site. Professor Marjorie Chan, the chair of the university’s geology and geophysics department co-wrote the paper.
Courtesy Roger SeilerDuring the early Jurassic period - 190 million years ago - the region was a desert larger than today’s Sahara desert, and it’s thought the tracksite was located at an oasis where a variety of dinosaurs gathered for water. Today the ancient desert is a layer of sandstone located in the Coyote Buttes North area of the Paria Canyon-Vermilion Cliffs Wilderness along the Arizona and Utah border. Thousands of footprints litter the three-quarter-acre area – in some cases dozens of tracks per square yard. Walking across the tracksite reminded Seiler and Chan of a popular arcade game.
“Get out there and try stepping in their footsteps, and you feel like you are playing the game ‘Dance Dance Revolution’ that teenagers dance on,” said Chan. “This kind of reminded me of that – a dinosaur dance floor – because there are so many tracks and a variety of different tracks.”
Four separate types of tracks have been identified at the trample site along with some very rare dinosaur tail-drag marks. The study of trace fossils such as these is called ichnolology. The science has earned a growing respect in recent years after being long regarded as a secondary field of study. Major strides have been made in dinosaur behavior from studying the footprints they left behind. Since it’s difficult to ascertain the exact identity of the track maker (unless you find its skeleton at the end of its footsteps), dinosaur footprints are given their own classification such as Grallator, Eubrontes, and Sauropodomorph. You can read more about dinosaur track names here.
For a long time the footprints at Coyote Buttes North were thought to be nothing more than naturally occurring potholes eroded by water out of the Navajo Sandstone Formation. That opinion is still held in some circles but Seiler and Chan are convinced they were made by dinosaurs and display many footprint traits.
Courtesy Winston SeilerIf you’re interested in viewing the trackway yourself - get in line. Access to the area requires a permit (and a $7 fee) and advanced permit sales are already backlogged four months out. Call 435) 688-3246 or go online at http://www.blm.gov/az/st/en/arolrsmain.html (and click Coyote Buttes) for information. You can also take a chance to acquire one of the 10 additional daily permits issued a day prior to your visit to the site at the Paria Contact Station between March 15 and November 14 or at the Bureau of Land Management (BLM) Field Office in Kanab, Utah between November 15 – March 14.
Courtesy Nancy StevensThe first dinosaur tracks discovered on the Arabian Peninsula are presenting science with new information about dinosaur herding behavior, and the global patterns of their evolution.
A series of parallel tracks made by 11 individual sauropods and a set of ornithopod footprints cutting across them was discovered about 28 miles north of Sana'a, the capitol of the Republic of Yemen. The sauropod footprints show varying sizes meaning the trackway was probably made by a herd of both adults and their smaller offspring.
"Smaller individuals had shorter stride lengths, and took more steps to keep up with the larger individuals," said Nancy Stevens, an assistant professor of paleontology at Ohio University in Athens, Ohio. Stevens co-authored the paper with Anne Schulp, a paleontologist at the Netherland’s University of Maastricht. The paper can be found online at PloS ONE.
A sauropod is one those huge, long-necked, small-headed herbivores with an equally long tail. When viewed from the side, sauropods remind you of a gigantic snake with tree-trunk legs digesting an elephant-sized meal. An ornithopod, on the other hand, is a smaller (about the size of a school bus!) plant-eater that walked on two legs (bipedal).
The dinosaurs produced the tracks along the shoreline of an ancient waterway that existed during the Jurassic Period nearly 150 million years ago. "This mudflat would have been like a highway for them, with little tree cover," Anne Schulp said.
Fossils related to these same types of dinosaurs -- and of the same age -- have been found elsewhere in eastern Africa, adding to the contention that they co-existed when the Arabian Peninsula was fully connected to the African continent. Today, the Red Sea separates the two landmasses.
Ichnology is the study of trace fossils, which can be anything created by an animal while it was alive. These include footprints, coprolites (fossil dung), skin impressions, bite marks, signs of burrowing, etc. Non-organic evidence such as ripple marks and raindrops are sometimes included in the study. Footprints are sometimes referred to as ichnites.
By the way, a new exhibit in the Dinosaurs and Fossils gallery here at the Science Museum of Minnesota displays some trackways from the Coconino Formation in Northern Arizona. The tracks are believed to have been preserved in sandstone by a four-legged mammal-like reptile that lived some 260 million years ago during the Permian period. We’ve also covered the science of Ichnology earlier in these pages.
Courtesy Nancy StevensBack on the Arabian Peninsula, careful measurements were taken of each track and it’s relationship to nearby footprints. Data from print dimensions and stride length can reveal much about the size and speed of the track maker. The sauropod adults were estimated to have reached 10 to 13 feet in height at the hips and shoulders. The longest sauropod trackway, composed of 16 individual prints measured about 16 meters (about 53 feet). Stevens and Schulp believe it could extend even further once the northern end of the trackway’s limestone layer is exposed.
"We have just scratched the surface," Dr. Schulp said. "We're pretty sure there's a lot more to discover out there."
Courtesy Mark RyanThere have been a couple of recent reports about new prehistoric tracks being discovered. The first was the report from Montana of what could be a rare footprint Tyrannosaurus rex. A second discovery involves some 315 million year-old reptile tracks found
recently in New Brunswick in Canada,
The two discoveries are the latest in the science of Ichnology, a specialized branch of paleontology that studies the trace fossils of prehistoric creatures. Trace fossils can be anything that the behavior of an ancient creature has left in the fossil record, such as footprints, borings, burrows, eggs, coprolites etc., anything besides its dead remains. Gene made a recent post about burrowing dinosaurs. The burrow dug by the dinosaur would be classified as a trace fossil. But the bones found at the bottom of the burrow would not.
But since the Object of the Month for November here at the Science Museum of Minnesota is fossil animal tracks, I thought I’d muse a bit about them, specifically dinosaur tracks, a favorite subject of mine.
Courtesy Mark RyanThe first recorded dinosaur trackway came to light in 1802 when Pliny Moody, a 14-year-old farm boy, in South Hadley, Massachusetts plowed up a slab of red rock containing several three-toed footprints. Dinosaurs hadn’t even been imagined yet, so the tracks were attributed to giant birds –Noah’s Ravens– as the local doctor called them. Of course, he wasn’t far off since today’s birds are considered descendents of dinosaurs.
Three decades later, Reverend Edward Hitchcock who was president of Amherst College became fascinated with the tracks and started to collect them in earnest. Between 1836 and 1865 he amassed huge numbers of fossil tracks that today make up the world’s largest collection and are held in the newly completed Amherst College Museum of Natural History in Amherst, MA. Hitchcock did extensive study of the trace fossils for the rest of his life, and was the first to classify them into a Linnean system that is still used today. He even made large stony books of the prints by binding together slabs of complementing casts and molds. But in the end, he just couldn’t reconcile his religious beliefs with the evidence the tracks presented and went to his grave still holding on to his belief that they had been made by giant birds.
In 1858, the world’s first nearly complete dinosaur skeleton (Hadrosaurus foulkii) was discovered on John Hopkins’ farm in Haddonfield, NJ and put on public display at the Academy of Natural Sciences in Philadelphia. It was the start of the public’s fascination with dinosaurs that continues to this day. Unfortunately, as more and more dinosaur bones were found, the interest in their tracks diminished.
But in the past two decades new interest in fossil footprints has flared up as scientists begin to realize their value in determining dinosaur behavior. Luckily, dinosaur footprints are extremely abundant, and can be found as single prints or as trackways, sometimes hundreds of yards in length. One trackway in central Colorado called the "Dinosaur Freeway" is suspected to continue for hundreds of miles into New Mexico!
Fossil footprints can give scientists insight into a creature’s behavior revealing such information as locomotion, stride and speed, foot and leg anatomy, chronology, ecology, and geographic distribution.
The tracks are found, generally, in three forms: casts, true prints, and underprints. A cast is formed when the original imprint is filled with sediment that hardens into rock. True prints form when the animal leaves a direct imprint in the ground surface it steps on. Underprints are created when the weight and pressure of the dinosaur’s foot causes it to press into layers beneath the thin ground it steps on. Underprints usually don’t contain the detail of foot structure that a true print will sometimes reveal.
Because skeletal remains are seldom found along with tracks, it’s nearly impossible to say which exact species created them, so thanks to Edward Hitchcock fossil footprints have their own classification. The reverend’s original classifications contained genera such as Grallator, Eubrontes, and Anomoepus, but new names continue to be added as new tracks are uncovered. Take for instance, Dr. Phil Manning’s above mentioned recent discovery of a large therapod footprint. Because of its size and structure and the location it was found, it can be speculated that the trackmaker was a Tyrannosaurus rex. But because it’s not certain that that’s the case, the track would be attributed to a T-rex but would be called a Tyrannosauripus, a genus name meaning “tyrant lizard foot”. Dr. Manning could make it more specific by add a species tag resulting in something like Tyrannosauripus manningnensis.
In general, tracks are described by the size and shape of the footprint, the number and arrangement of digits, claw and heel marks, interdigital webbing and skin impression.
Some well-known tracksites in the United States include St. George Dinosaur Discovery Site in Utah, the Red Gulch tracksite in Wyoming, Dinosaur Ridge in Colorado, Dinosaur Valley State Park in Glen Rose, Texas, Clayton Lake State Park in New Mexico, and of course, Dinosaur State Park in Rocky Hill, Connecticut.