Horn of the last dinosaur discovered

Fossil is from the last ten thousand years before the end of the Cretaceous

Primitive Mammals on a Triceratops Skeleton © Mark Hallett
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In a rock formation in the US state of Montana, researchers have discovered a fossil horn of the youngest known dinosaur. The animal probably lived only a few thousand to ten thousand years before the great mass extinction 65 million years ago. "This discovery provides some evidence that the dinosaurs did not die out before the meteorite struck, " says study leader Tyler Lyson of Yale University.

According to popular theory, a meteor impact is said to have triggered the global catastrophe. Whether the dinosaurs still existed at this time is controversial. Fossil records from the time immediately preceding the disaster were missing so far. According to the researchers, the current find could close this gap. As they report in the journal "Biology Letters", they found the fossil dinosaur horn just 13 centimeters below the so-called KT layer. This rock layer marks the time of mass extinction and thus the end of the Cretaceous. So far, the area of ​​three meters under the boundary layer was considered largely dinosaur-free.

"Our discovery suggests that this three-meter gap does not exist, " the researchers say. At least some dinosaurs had apparently gone well until the impact. The proximity of their find to the KT-Schicht prove this.

Random find at the KT border

The discovery of the dinosaur fossil in the Hell Creek Formation in eastern Montana was unplanned, reports Lyson. Actually, in the summer of 2010, Yale paleontologists searched for mammal fossils from the post-mass extinction period. By chance, they found the brown horn of a ceratopsian in a sediment deposit. The most well-known representative of these herbivorous dinosaurs is the horned and heavily armored Triceratops.

In order to determine the exact location of the fossil in relation to the KT limit, the researchers had samples of the surrounding soil layers analyzed in the laboratory. The indicator for the boundary layer is, among other things, the sudden decrease of Cretaceous pollen in the sediment and an enrichment with the rare element iridium. The analysis showed that the horn was only about 13 centimeters below the KT layer - as close as no other dinosaur found before. display

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Dinosaurs lived ten thousand years before the mass extinction

The dinosaur - probably a Triceratops - probably lived at least a thousand to ten thousand years before the mass extinction, the researchers say. However, a more precise age determination of the fossil was not possible so far. Due to its location in an intact claystone layer, however, they rule out that it was subsequently washed from its older position to its position.

The research team is currently investigating further fossils buried near the boundary layer. In her opinion many well-known finds may have been located much closer to the KT border than expected. "We should be able to confirm this by using soil analysis technology instead of assessing the location of the boundary layer only by visually assessing the rock formations, as was customary in the past, " says Lyson, (Biology Letters, DOI: 10.1098 / rsbl.2011.047)

(Biology Letters / Yale University, 14.07.2011 - NPO)