Past Time

The oldest basilisk lizard from North America, described by Jack Conrad from NYIT College of Osteopathic Medicine, shows the 48 million year old animal was part of an ancient lush jungle ecosystem…in the middle of Wyoming. The beautifully preserved skull has important stories to tell about the evolution of the lizards most famous for their ability to scamper across the water, but it also reveals what North America was like during a greenhouse world that wasn’t all that different from what our planet’s future may look like.

Here’s the link to the original article.

And here’s what some modern basilisks can do when they get near the water’s edge:

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Dating fossils might sound like Saturday night for a paleontologist, but it’s serious science! In a new study, a group of physicists and paleontologists teamed up to re-date one of the most complete skeletons of a human relative ever discovered.

The skeleton was discovered in a cave in South Africa twenty years ago, but the geology of the cave made it tough to figure out how long ago the animal, nicknamed “Little Foot” was washed in an buried. The date paleontologists were working with was 2 million years old, making this specimen that belongs to the genus Australopithecus a much younger animal than its cousin Lucy (Australopithecus afarensis).

Using a new technique that looks at how the atoms in the sand grains around the specimen changed after being sealed in the cave, away from cosmic ray bombardment, the team discovered the specimen is 3.67 million years old! That put the South African animal on the landscape at the same time as Lucy. That means two species of Australopithecus were wandering around at the same time. How did they share the landscape? Which species is more closely related to us? The paleontologists working on Little Foot are still getting it ready for a full anatomical description, but this new study presents a new way to date fossils once thought impossible to get an age from and makes us even more eager to know more about the anatomy of this ancient cousin of ours!

Check out this video if you want to learn more about the machine used by the physicists to date the sand around the Little Foot specimen:

The study:

Darryl E. Granger, Ryan J. Gibbon, Kathleen Kuman, Ronald J. Clarke, Laurent Bruxelles, and Marc W. Caffee. 2015. New cosmogenic burial ages for Sterkfontein Member 2 Australopithecus and Member 5 Oldowan. Nature. DOI:10.1038/nature14268

Brontosaurus was an extinct name for an extinct animal, but a new study brings the “Thunder Lizard” title roaring back to life! But how does a name get dropped, and how does it get brought back again? Follow us into the winding world of paleontology taxonomy, the study of names.

In the 1870s two giant hip bones were found and named by one of the great paleontologists of the age: Othniel Marsh. He thought there were a few differences and called one Apatosaurus ajax and the other, named a few years later, Brontosaurus excelsus.

The Brontosaurus and Apatosaurus parts of those names are the genus, and the second part – excelsus and ajax – are the species. In 1903 another paleontologist, Elmer Riggs, decided they weren’t different enough to be different genera. Apatosaurs was the older genus, so Brontosaurus excelsus became Apatosaurus excelsus to show other scientists how closely related it was to Apatosaurus ajax. They were two species in the same genus.

Infographic created by 4.0 PeerJ

A new study looked at every specimen from the family that includes Apatosaurus that has ever been collected: Diplodocidae. The family Diplodocidae includes long-necked dinosaurs with horse-like faces and whip-like tails. Some of the specimens were collected 150 years ago but were never really scrutinized before.

In the new analysis, the specimens once called Brontosaurus  were found to be related to different specimens from Apatosaurus ajax. They aren’t each other’s closest relatives anymore, so the name Brotosaurus was brought back to describe this newly discovered cluster of specimens that are united by newly discovered anatomical features such as Brontosaurus’s narrower neck.

This is just one more hypothesis for dinosaur relationships. There are more fossils to discover in the field and in museum collections and paleontologists will keep hunting for more relatives of the Thunder lizard and its kin!

The study:

Emanuel Tschopp, Octávio Mateus, and Roger B.J. Benson. 2015. A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda). PeerJ 3:e857 https://dx.doi.org/10.7717/peerj.857

In a study published in the Proceedings of the Royal Society B, Rodolfo Salas-Gismondi and other paleontontologists described the crocodiles from a gigantic wetland that predated the Amazon. Ten million years ago there was the giant Purussarus, the duck-billed Mourasuchus, the tube-snouted gharial-like croc, a coyote-like croc similar to Paleosuchus, and three new crocs with broad teeth perfect for crushing shells: Kuttanacaiman, Caiman wannlangstoni, and Gnatusuchus pebasensuis. This is the largest number of croc species living in the same place at the same time that the Earth has ever known. How did they find room for each other in the ecosystem? These new animals from Peru shed light on the South American croc ecosystem before the Amazon River started to flow and tell us we have a lot to learn about the ways crocs can make a living.

The crocodiles from the Pebas Formation were a diverse bunch. The fossil new species are shown on the left drawn by Javier Herbozo, the giant Purussaurus was drawn by Nobu Tamura, Mourasuchus-like Stomatosuchus (they look similar, but are distantly related) by Dmitry Bogdanov.

Drawing of the new croc species from the Pebas Formation in northeastern Peru by Javier Herbozo. All three are closely related to caimans, a group of crocodilians closely related to alligators. Gnatusuchus has blunted teeth that would have made it a formidable shellfish eater.

Citation:

Rudolfo Salas-Gismondi, John J. Flynn, Patrice Baby, Julia V. Tejada-Lara, Frank P. Wesselingh, Pierre-Olivier Antoine. 2015. A Miocene hyperdiverse crocodylian community reveals peculiar trophic dynamics in proto-Amazonian mega-wetlands. Proceedings of the Royal Society B.