Paleontologists recently announced their conclusion that a huge predatory carcharodontosaurid roamed land in what is now western North America during the late Cretaceous period, forcing tyrannosaurs – the family of dinosaurs that included Tyrannosaurus rex – to be lesser predators on the prehistoric food chain.
The newly-discovered animal, dubbed Siats meekerorum, lived alongside tyrannosaurids and competed with them for food. It is the third-largest carnivore ever found on the continent.
“It’s been 63 years since a predator of this size has been named from North America,” Lindsay Zanno, a North Carolina State University paleontologist who is the lead author of the paper describing the dinosaur. “You can’t imagine how thrilled we were to see the bones of this behemoth poking out of the hillside.”
The last carcharodontosaurid discovered in North America was found in 1950. Called Acrocanthosaurus, that 40 foot-long dinosaur lived at least 10 million years earlier than Siats meekerorum.
The animal discovered by Zanno and her colleague Peter Makovicky, a paleontologist at Chicago’s Field Museum, would have been about 30 feet long and weighed about four tons.
Its discovery may be the missing piece to a puzzle that has gone unanswered by science for many years: What was the top predator between the time that Acrocanthosaurus went extinct and Tyrannosaurus rex rose to the top of the food chain during the late Cretaceous period?
“The huge size difference certainly suggests that tyrannosaurs were held in check by carcharodontosaurs, and only evolved into enormous apex predators after the carcharodontosaurs disappeared,” Makovicky said.
Zanno and Makovicky found the fossils that were later determined to be those of Siats in Utah’s Cedar Mountain Formation in 2008.
Siats meekerorum is named to honor a family that has supported the research efforts of Field Museum paleontologists.
Artist’s conception of Siats meekerorum by Jorge Gonzales, courtesy North Carolina State University.
Researchers have published a paper that claims the first possible discovery of a moon outside of our solar system.
The study, which was published online on Dec. 13, depends on a methodology called microlensing, in which scientists measure the degree to which starlight is refracted by the presence of a gravity-producing object.
Astronomers observed, using several telescopes all over the world, the magnification of light from a distant star to 70 times its ordinary brightness. They they observed a second brightening of the light, but to a lesser extent, which may indicate that the first object that bent the light – possibly an exoplanet – was followed into the path of the starlight by an exomoon.
The results of the research team’s observations do not assure that this scenario is a certainty.
“The data are well fit by this exomoon model, but an alternate star+planet model fits the data almost as well,” the researchers concluded.
The exomoon is hypothesized to exist in a system with an exoplanet that does not orbit a star.
The paper is published at Arxiv and has not yet been peer-reviewed.