Paleontologists Discover Oldest Mammalian Tooth Marks
Paleontologists discovered the oldest mammalian tooth marks on the bones of ancient animals, including several large dinosaurs. The findings were reported in a paper published online in the journal Paleontology on June 16. The image above is a close-up of the tooth marks gouged into the rib bone of a large dinosaur by a small mammal that lived 75 million years ago.
Nicholas Longrich of Yale University and Michael J. Ryan of the Cleveland Museum of Natural History came across several of the bones while studying the collections of the University of Alberta Laboratory for Vertebrate Palaeontology and the Royal Tyrrell Museum of Palaeontology. They also found additional bones displaying tooth marks during fieldwork in Alberta, Canada. The bones are all from the Late Cretaceous epoch and date back about 75 million years.
Longrich said, "The marks stood out for me because I remember seeing the gnaw marks on the antlers of a deer my father brought home when I was young. So when I saw it in the fossils, it was something I paid attention to."
The researchers believe the marks were made by mammals because they were created by opposing pairs of teeth. This is a trait seen only in mammals from that time period. They think they were most likely made by multituberculates, an extinct branch of mammals that resemble rodents and had paired upper and lower incisors. The paleontologists discovered tooth marks on a femur bone from a Champsosaurus, an aquatic reptile that grew up to five feet long; the rib of a dinosaur, most likely a hadrosaurid or ceratopsid; the femur of another large dinosaur that was likely an ornithischian; and a lower jaw bone from a small marsupial.
The animals that made the marks were about the size of a squirrel. Longrich says, "The bones were kind of a nutritional supplement for these animals."
National Geographic will air "When Crocs Ate Dinosaurs" - an episode of Expedition Week - on November 21st.
Some hundred million years ago, crocodiles were the ruling T. rexes of the waters. They galloped on land, ambushed prey at the river's edge ... even terrorized dinosaurs. And more, these swift predators' cousins evolved through the ages into the modern crocs we know today. Now, armed with newly discovered prehistoric crocodile bones, Explorer-in-Residence Dr. Paul Sereno is determined to bring the ancient creatures to life - and tell their fantastic untold story. Learn about a croc that pursued prey across land, a supercroc that locked its jaws around dinos, and even one with a startlingly canine face. Blending art, forensics and biology, Sereno's team recreates a lost world of strange Cretaceous crocs that paleontology forgot.
One can easily imagine a crocodile eating small dinosaurs but watch what happens about 2:10 into the clip when the prehistoric boar-croc decides to go after a sauropod.
Dinosaurs Roam the Los Angeles Natural History Museum
You can interact with some realistic looking dinosaurs at the Los Angeles Natural History Museum. The L.A. Times reports on these sometimes free-roaming actor-puppeteer dinos.
Without any ballyhoo, the museum launched a new attraction in June called Dinosaur Encounters, in which actor-puppeteers don lifelike T. rex or triceratops suits and spend 20 minutes demonstrating how scientists believe baby dinos behaved. Usually they work with interpreter-handlers, but sometimes they just roam free and meet their public. Which is how a museum-goer's video of a grunting, bemused, 7-foot-tall and 14-foot-long T. rex inspecting babes-in-arms and other humans at close range came to be posted on MySpacetv on Thursday. "Real Live Dinosaur" shot to No. 1 on MySpace's daily video chart, attracting more than 215,000 viewers by early evening -- far outstripping "Cindy and Heidi Bare It All." That clip from TMZ featured stills of Crawford and Klum yachting au naturel, their modesty preserved by strategically placed black bars.
A MySpace page has been set up for the dinosaurs here.
Newly Discovered Dinosaurs Ate Like Hyenas and Sharks
The fossils of two meat-eating dinosaurs named Eocarcharia and Kryptops have been discovered in the Sahara Desert. The newly discovered dinosaurs appear in a paper this month in the scientific journal Acta Palaeontologica Polonica. The fossils were discovered in 2000 on an expedition led by University of Chicago paleontologist Paul Sereno.
Sereno and co-author paleontologist Stephen Brusatte of the University of Bristol say the new fossils provide a glimpse of an earlier stage in the evolution of the bizarre meat-eaters of Gondwana, the southern landmass. "T-rex has become such a fixture of Cretaceous lore, most people don't realize that no tyrannosaur ever set foot on a southern continent," said Sereno. Instead, particularly distinctive meat-eaters arose, some of which bore no resemblance to the "tyrant king," beyond their appetites for fresh meat.
The two dinosaurs have distinctive faces. Kryptops probably ate mostly from already dead carcasses (like hyenas) and Eocarcharia dinops ate live prey (like sharks).
Short-snouted Kryptops palaios, or "old hidden face," was named for the horny covering that appears to have covered nearly all of its face. "A fast, two-legged hyena gnawing and pulling apart a carcass," remarked even Brusatte, "is how we might best imagine Kryptops' dining habits." Kryptops also had short, armored jaws with small teeth. The scientists say these teeth make Krptops better at eating from a carcass than trying to eat live prey.
Eocarcharia dinops - or "fierce-eyed dawn shark" - was named for its blade-shaped teeth and prominent bony eyebrow. Unlike Kryptops, the scientists say its teeth were designed for disabling live prey and severing body parts. Eocarcharia and kin (called carcharodontosaurids) gave rise to the largest predators on southern continents, matching or exceeding Tyrannosaurus in size. Eocarcharia's brow was swollen into a massive band of bone, giving it a menacing glare.
Both of the newly discovered dinosaurs were about 25-feet long. Project Exploration has more information about the new dinosaurs, their contemporary species and Cretaceous habitat, and the expedition on which the fossils were discovered.
New Fossils and Hi-Tech Leads to Dinosaur Breakthroughs
Newsweek has a feature on dinosaurs and how recent fossil discoveries and new technologies are uncovering tons of new information about dinosaurs. Recent fossil discoveries include dinosaurs with feathers and intact dinosaurs with fossilized blood,
skin and possibly organs. Using powerful computers and improved scanning
tools scientists are also able to go back and obtain more information
from previously discovered fossils. Here an excerpt from the discover
of the duck-billed herbivore with skin:
It was on a fossil-hunting trip in the summer of 2000 that Leonardo's fossil was discovered. Murphy returned the following summer to excavate Leonardo, a member of the well-known species Brachylophosaurus -- a Late-Cretaceous duck-billed herbivore that grew as long as 35 feet. As his team worked on a forelimb, a volunteer saw something unusual and called to Murphy. "I took one look and said, 'Oh my God, this is skin'." When he realized he was dealing with more than a skeleton, Murphy had to revise his plan; instead of digging out the bones one by one, he had his team dig around the 23-foot-long specimen, so it could be moved to his research lab in one six-ton chunk.
Murphy hopes to transport Leonardo -- still half embedded in sedimentary rock -- to Hill Air Force Base in Utah, which has one of the world's largest CT scanners. There the heart, lung, kidneys and other organs, if they are indeed preserved inside, can be visualized and even modeled in three dimensions.
A CT scan of an entire dinosaur mummy would be an astonishing achievement, writes Adler, but no more so, perhaps, than what Mary H. Schweitzer, a biologist at North Carolina State University, accomplished with a mere fragment of T. rex bone. Schweitzer put the fossil in a weak acid and recovered a flexible substance that resembled collagen, the major organic component of bone, plus traces of red blood cells, which appear to have nuclei, holding out the possibility of recovering genetic material. And when Kent Stevens, a computer scientist at the University of Oregon, modeled on his computer the bones of the large long-necked sauropods of the late Jurassic Period, he discovered their natural position seems to lie almost parallel to the ground, or even below horizontal-an unwelcome revelation to many laymen who usually see them depicted standing foursquare with their heads high above the ground, like fat, short-legged giraffes.
Newsweek has a 
