“Lost World” of Dinosaurs – Controversial Evidence from the USA

Did some dinosaurs survive beyond the Cretaceous mass extinction event?

A team of scientists from the U.S. Geological Survey have published a paper stating that they have found further evidence that some kinds of dinosaur lived after the mass extinction event that is supposed to have led to their demise.

Cretaceous Mass Extinction

In a paper published in the scientific journal “Palaeontologia Electronica“, the team of geologists led by James E. Fassett, of the U.S. Geological Survey claim that 34 fossilised skeletal elements of a duck-billed dinosaur (hadrosaur) indicate that some dinosaurs survived into the Tertiary.  The fossil evidence is supported by paleomagnetic data (magnetic analysis) and chemical analysis of the fossil bearing rock.

The rock containing the hadrosaur has a different magnetic signature and rare Earth element analysis compared to strata known to date from the K-T boundary that marks the end of the Age of Reptiles.  This data indicates that the strata in which the hadrosaur remains were found, is probably younger than the K-T boundary sediments.  This is evidence that some dinosaurs may have survived into the Palaeogene period.

Emeritus scientist James Fassett, has published a number of papers detailing controversial evidence of dinosaurs living beyond the mass extinction event.  His latest paper concerns a study of Palaeogene-aged strata from the Ojo Alamo Sandstone Formation in the San Juan basin, an area of sedimentary rock that covers parts of New Mexico and Colorado.

Did Some Non-avian Dinosaurs Survive?

Working from his base at Santa Fe, Mexico, James has stated on numerous occasions that some types of dinosaurs survived beyond the Cretaceous, as well as hadrosaurs, he claims that ceratopsians, tyrannosaurs and ankylosaurs all survived into the Cenozoic.

Such claims spark a lot of debate amongst scientists, as although they are unsure as what series of events led to the wiping out of the dinosaurs, pterosaurs and approximately 65% of all life on Earth, there have been very few fossils found of dinosaurs outside Mesozoic sediments.

Palaeontologists refer to these types of fossils as “survivor finds” and although some dinosaur fossils have been found in younger aged sediments, most scientists believe that they have been eroded out of older rocks and then redeposited in younger strata.

Commenting on the paper, Hans-Dieter Sues, Associate Director for research and Collection at the Smithsonian Institute in Washington stated:

“Every few years, someone claims to have found Palaeocene surviving dinosaurs, but so far, fossils have eventually turned out to be re-deposited older remains”.

“Survivor Finds”

The fossils in question, these so called “survivor finds” are at first fossilised in sand or mud, but have their fossils exposed again by natural erosion forces such as river erosion.  The bones are washed out and then re-deposited in younger strata, making it look like some dinosaurs survived into the Tertiary.

The finding of 34 individual bones, believed to represent a single animal, refutes that theory in this case according to the U.S. Geological Survey team.  They argue that the associated hadrosaur fossils would have been dispersed had this fossil been subject to re-deposition.  The river would have dispersed the bones over a wide area, not left them in close association and they would have shown signs of damage from the erosion process.  Fassett and his team state that the fossils are in “pristine” condition, indicating that they were not damaged as a result of re-deposition.  This is evidence that the fossilised elements were deposited together, just the once – indicating a Cenozoic hadrosaur.

For models and replicas of Late Cretaceous prehistoric animals and other extinct creatures: Bullyland Prehistoric Life Models and Figures.

Working with colleagues at the U.S. Geological Survey in Denver, Fassett and his team examined concentrations of uranium and rare-Earth metals in the fossilised bones and surrounding matrix.

Fassett commented:

“I thought if we could determine the trace-element compositions of the bones, we might discover that the [older] Cretaceous bones had a different chemical fingerprint than the [younger Palaeocene/Palaeogene] bones do”.

The resulting analysis proved that the rocks had different chemical compositions indicating that they did have different geological dates.

A number of theories have been put forward regarding the extinction of the dinosaurs, the most popular theory (first put forward by Luis and Walter Alvarez), is that a huge meteorite or asteroid struck the Yucatan Peninsula.  This catastrophic event resulted in the demise of the dinosaurs.

To read more about the Asteroid Strike Theory: Sulphureous Skies Linked to Dinosaur Demise.

Fassett, who supports the Yucatan impact theory, stated that he could not explain why dinosaurs may have survived longer in some parts of the world than others.

“One guess is that the survivors lived in the northernmost parts of North America, at the greatest distance from the impact site, and then they migrated south”.

However, he did concede that there had been very few fossils of dinosaurs found dating from Tertiary strata.  There remains a lack of evidence to support the survival of dinosaurs beyond the Cretaceous mass extinction, although as Fassett and his team have reported, it is quite feasible that small, isolated groups of dinosaurs could have survived for a short-time following the extinction event.

The fossilised hadrosaur remains in the Palaeogene strata is dated some 500,000 years after the deposition of the K-T boundary.

Hans-Dieter Sues stated:

“There is no a priori reason that dinosaurs could not have survived in some places”