Dinosaur-Extinction Asteroid Impact Occurred During Northern Hemisphere's Spring
2022-02-25
About 66 million years ago, an asteroid impact caused the extinction of 75% of species, including the dinosaurs. The impact is believed to have occurred off the coast of the present-day Yucatán Peninsula in Mexico. According to a paper published in the scientific journal Nature on February 23, "the asteroid impact occurred during spring in the Northern Hemisphere (and autumn in the Southern Hemisphere)."
A detailed examination of several sturgeon fossils found in North Dakota in 2017 revealed that they died within about an hour of the impact. By focusing on the fact that fish bone growth rates differ by season, researchers verified that they died in the spring.
Furthermore, research findings on fish from the end of the Cretaceous period in North Dakota, believed to have died at the time of the impact, were also published in the journal Scientific Reports in December 2021. Investigations using different specimens (fossils) and different methods yielded nearly the same result: "they died in the spring."
Were There Three Species of Tyrannosaurus?
2022-03-04
For many years, the genus Tyrannosaurus was thought to consist of only one species, rex. "Tyrannosaurus" and "T-Rex" were synonymous.
Gregory Scott Paul (an illustrator and independent dinosaur researcher) published a paper in the journal "Evolutionary Biology" on March 1. He proposed that the body shape of Tyrannosaurus can be classified into three patterns, each of which should be described as a separate species. This conclusion is based on data obtained from measuring the femurs and lower jaw teeth of 37 Tyrannosaurus (fossils).
In addition to "rex," which means <tyrant>, he proposed two new species names: "regina," meaning <queen>, and "imperator," meaning <emperor>.
However, many paleontologists, including world authorities on Tyrannosaurus, are skeptical of Gregory Scott Paul's paper.
Just as humans have differences in physique based on sex, age, and individual variation, Tyrannosaurus likely had different body types depending on sex, growth stage, and individual. In 2020, Tyrannosaurus authority Thomas Carr analyzed 1,850 morphological features of Tyrannosaurus but found no features indicating species differences.
Further discoveries and research are needed to conclude whether Tyrannosaurus should be classified as a single species, rex, or multiple species.
New Dinosaur Paralitherizinosaurus from Hokkaido
2022-05-10
A fossil discovered in 2000 in a stratum in Nakagawa, Hokkaido (Osoushinai Formation of the Yezo Group), has been identified as a new genus and species of therizinosaurid dinosaur. Research was conducted by the Hokkaido University Museum, Okayama University of Science, and the Nakagawa-cho Eco Museum Center, among others. It has been named "Paralitherizinosaurus japonicus" (meaning "therizinosaur from the coast of Japan").
Excavated from a Late Cretaceous stratum (about 83 million years old), this discovery indicates that therizinosaurs in East Asia had a wide habitat and were adapted to diverse environments for a long time.
Giant Dinosaur with Large Head and Short Forelimbs in Argentina
2022-07-20
A fossil of a giant new species of carnivorous dinosaur has been found in the northern Patagonia region of Argentina.
The new theropod dinosaur is estimated to have been about 11 meters long and weighed 4 tons. It lived in Patagonia, which was a lush forested area during the Cretaceous period, about 90 to 100 million years ago. A feature of this carnivorous dinosaur, named "Meraxes gigas," is its short arms. It is thought that it probably could not catch prey with these arms, nor could it bring them to its mouth even when extended.