Past Time

Under the canopy of an ancient fern forest near the border of Arizona and New Mexico a colossal crocodile-like reptile took a bite out of an even larger, toothy giant. The attack failed and the victim limped on to fight another day, until its carcass was finally pillaged by another scaly monster and smaller, pickier scavengers. Studying bones collected over a century ago, scientists are now able to reconstruct these scenes from the ancient Wild West using new digital tools familiar to fans of C.S.I.

Stephanie Drumheller, from the University of Tennessee, and her team first noticed the fossils, collected in 1913, in museum collections. They observed deep bite marks in two separate thigh bone specimens that would have belonged to two rauisuchians (row-ay-soo-keeans), wolf-like reptiles with the head of Tyrannosaurus rex. These 30-foot-long carnivores were supposed to be at the top of the food chain 218 million years ago in the Chinle Formation, an ancient ecosystem preserved in flame-red rock that gives the Painted Desert its name. Who took the bite out of these meat-eating giants?

Fortunately, the attacker left a weapon at the scene of the crime. Deeply embedded near the hip joint in one of the bones is a massive, curved tooth. Using the same CT-scanning technology doctors use to create 3D images of their patients, Drumheller and her team digitally extracted the tooth, identifying the powerful predator as a 25-foot long phytosaur (fight-o-sore). Scientists thought the slender-snouted, crocodile-like reptile was a fish specialist, but this new evidence shows it fought one of the largest carnivores on the planet.

CT-scanners are a new, important part of the fossil hunting toolkit, allowing scientists to digitally dissect rare and delicate fossils to expose the secrets locked inside. Around the embedded tooth, Drumheller and her team digitally extracted healed bone, evidence that the rauisuchian escaped the phyotosaur’s attack and the wound had time to heal. Near the tooth are deep, unhealed bite marks, showing another large phytosaur attacked the same rauisuchian later, but there wasn’t time for that wound to heal. Closer to the knee are shallower, smaller tooth scratches, evidence of scavengers that picked over what was left behind by the phytosaur, just as modern vultures pick at a carcass once the lions have eaten their fill.

There are a lot of gigantic reptiles in the Chinle Formation and the hypothesis was that the large rauisuchians were the top of the land-based food chain, and phytosaurs were at the top of the aquatic fo

A new fossil shows an ancient reptile, Philydrosaurus, surrounded by young. Possible evidence that parental investment is a more ancient trait in land-based vertebrates than paleontologists thought!

Reptiles aren’t known for being great parents. When it comes to time and energy spent with the kids, mammals get all the glory. Birds also spend a lot of time with the chicks after they hatch, but this was though to be a recent phenomenon related to the evolution of flight. Then scientists noticed crocodiles guard and nurture their chicks and paleontologists found evidence of dinosaurs spending time with their young long after they hatched.

Okay, maybe being an invested parent is a mammal and archosaur (the group that contains crocodiles and dinosaurs and thus birds) thing. But most reptiles are pretty uninvolved parents, right?

A 125 million year old fossil from the Yixian Formation in China shakes up the story. The specimen preserves a 2 foot-long, adult Philydrosaurus — a choristodere reptile distantly related to lizards, turtles, crocodiles, and dinosaurs — surrounded by six juvenile Philydrosaurus. The group was buried together with no other fossils mixed in, suggesting this group of seven ancient reptiles are one of the oldest known families from the fossil record.

Because choristoderes are such early off-shoots from the reptile family tree, the team of paleontologists lead by Dr. Junchang Lü from the Chinese Academy of Geological Sciences hypothesize the adult Philydrosaurus was doing what reptile parents had been doing for a long time: investing and nurturing young.

This would mean living reptiles like snakes, turtles, and lizards lost this trait during their evolution while mammals, crocs, dinosaurs, and birds held onto the trait. Fossils that preserve parental behavior are extremely rare and this fossil is a valuable glimpse into the family lives of early reptiles!

Lü, Junchang, Yoshitsugu Kobayashi, D. Charles Deeming, and Yongqing Liu. 2014. Post-natal parental care in a Cretaceous diapsid from northeastern China. Geosciences Journal. DOI:10.1007/s12303-014-0047-1

Researchers lead by Hans-Dieter Sues from the Smithsonian Institution described a wealth of new giant, long-necked dinosaur material from Western Asia (Uzbekistan). They were able to reconstruct what the brain looked like and discvered the dinosaur, part of the lineage called “titanosaurs”, is closely related to animals from the far East of Asia, places like China and Laos. They decided there wasn’t enough of the giant to give it a name, but they know it and its relatives were able to make a living across the diverse enviroments of Asia 90 million years ago. This is further evidence that tintanosaurs were successful for much of the Age of Dinosaurs both on the Northern and Southern continents.

The study:

Conjuring up extinct environments, museums, books, and documentaries rely on art to show extinct animals revitalized in their ancient surroundings. This type of educational reconstruction is called Paleoart (or Palaeoart for the UK inclined). They are usually striking portraits of the weird place this planet used to be. But, you look at an image of a roamingTyrannosaurus rex without wondering, “How much of that is real?” How do we know its bulk, its color, its environment, or its behavior? Where does the science start and the art (and hypothesizing) begin? Julius Csotonyi, a Candian paleoartist, sat down with us to discuss how he assembles his images which are on display in natural history museums across North America and fill his recently published book, The Paleoart of Julius Csotonyi. A single landscape by Julius is a blend of the latest knowledge from paleontologists, zoologists, paleobotanists, geologists, and geochemists, and as new information is learned, he is ready to update his paintings and present the world with a more accurate glimpse into the ancient past.