Is It True That There Are No Dinosaur Remains In The Impact Layer?

Question: Is it true that there are no dinosaur remains in the impact layer?

Answer: Evidence in this regard is limited.

Explanation: Is It True That There Are No Dinosaur Remains In The Impact Layer?

Most scientists believe that an asteroid hit the earth and caused the dinosaur species’ mass extinction. The location of the impact has been identified near the Yucatan Peninsula in the Gulf of Mexico. Fossil evidence of dinosaurs existing even during the years leading up to the asteroid’s impact is limited.

Over the years, the evidence to corroborate such a seismic event has been limited. In 1980, physicist Luis Alvarez and his geologist son, Walter Alvarez, discovered that high levels of iridium were present in the K-T boundary. Formed 65 million years ago, this transition line was formed between the Cretaceous and Tertiary periods. While iridium is a common element in asteroids, it is extremely rare inside the Earth’s crust. 

Dinosaur fossils had yet to be found higher than about 9,8 feet beneath the K-T boundary. In essence, about 100,000 years of dinosaur existence had been unaccounted for. Most scientists believed that the dinosaurs expired gradually before the asteroid collided with earth. Other experts believe that a surge in volcanic activity caused the dispersal of ash into the Earth’s atmosphere. This reduced available sunlight, resulting in poor plant growth. This had an adverse effect on the herbivorous dinosaur’s diet. It also could’ve resulted in diminished inland water sources that provided suitable habitats for the dinosaurs. 

In 1991, paleontologist Peter Sheehan and his team discovered about 2,500 dinosaur fossils in Montana and North Dakota. This helped reduce the 9.8 feet fossil gap beneath the K-T boundary to less than 24 inches. In Colorado, dinosaur footprints were also located beneath the K-T boundary.

Earlier this year, fossils were discovered in the Tanis fossil site in North Dakota, USA. A leading expert in ornithischian dinosaurs, Professor Paul Barrett, has studied a fossilized leg discovered in the area. He believes it to be the relatively unknown Thescelosaurus. The fossilized leg shows no sign of disease, and there’s no evidence of bite marks administered by a scavenger. These factors led scientists to believe that the Thescelosaurus’ death was probably instant. Due to the position of the fossil in the sedimentary rock, it’s also thought that this dinosaur may have expired when the asteroid collided with the earth.

However, Prof Steve Brusatte is not convinced yet and states this evidence to be circumstantial. He theorizes that dinosaur species may have died off before the impact. The tremendous force of the impact caused these dinosaurs to be exhumed and re-interred once again. In this way, their demise appears concurrent with the asteroid strike.