Paleocene Dinosaurs

[Balaur]

I have been struggling with wether or not some non-avian dinosaurs lived briefly in the Paleocene. While there is no good evidence, I think that some dinosaurs probably did survive for a very short time in the Paleocene. So, what do you guys think about this? I think it is possible, but I will await further evidence.

[Pachyrhinosaurus]

I think dinosaur fossils may have been eroded out of their soil and reburied, or at least that's what Wikipedia says, it sounds very plausible, though. If someone were to find an articulated skeleton in palaeocene rocks, then I think that would be definitive evidence for palaeocene dinosaurs.

[Balaur]

I think dinosaur fossils may have been eroded out of their soil and reburied, or at least that's what Wikipedia says, it sounds very plausible, though. If someone were to find an articulated skeleton in palaeocene rocks, then I think that would be definitive evidence for palaeocene dinosaurs.

Yeah. I always imagine an animal like Troodon surviving for a few hundreds or just even a few thousand years after the Paleocene started. I think I was influinced by Dinosaur Revolution. 

[Splonkadumpocus]

From what I've read, it seems like the relevant fossils were reworked from Mesozoic rocks.

[SBell]

AFAIK, anytime an announcement is made about post-K dinosaurs (birds excluded, of course) it turns out to be reworked sediment. Most dino bones are well below the K/Pg boundary (where it is available for direct or near-direct correlation), the exceptions that are closer are quite rare (and may be reworked as well).

[Everything_Dinosaur]

Just picked up the thread on this, most of the claims for Cenozoic dinosaurs relate to re-deposition however, a few years ago we wrote an article on the Everything Dinosaur blog after Hadrosaur specimens were claimed to be from Palaeogene strata: Did some dinosaurs survive into the Palaeogene?

The information we received came from the U.S Geological survey?

[amargasaurus cazaui]

This entire issue was discussed to some degree in a previous thread, about the extinction event. Wings posted the published paper regarding the supposed dinosaur remains from the San Juan basin being referenced by this writer.In essence the paper examined the various issues and arrived at the conclusion that in the case of these fossils rather than the seperate bones being reworked, the explanation supported by the sediment layers was that the entire fossil bearing layer had been lifted and transposed over a younger geological layer creating the out of sequence fossil remains.

[SBell]

This entire issue was discussed to some degree in a previous thread, about the extinction event. Wings posted the published paper regarding the supposed dinosaur remains from the San Juan basin being referenced by this writer.In essence the paper examined the various issues and arrived at the conclusion that in the case of these fossils rather than the seperate bones being reworked, the explanation supported by the sediment layers was that the entire fossil bearing layer had been lifted and transposed over a younger geological layer creating the out of sequence fossil remains.

So really big tectonic reworking!

[Dinoguy2]

This entire issue was discussed to some degree in a previous thread, about the extinction event. Wings posted the published paper regarding the supposed dinosaur remains from the San Juan basin being referenced by this writer.In essence the paper examined the various issues and arrived at the conclusion that in the case of these fossils rather than the seperate bones being reworked, the explanation supported by the sediment layers was that the entire fossil bearing layer had been lifted and transposed over a younger geological layer creating the out of sequence fossil remains.

So really big tectonic reworking!

Not tectonic, just re-buiral. Let's say a Triceratops skeleton eroded mostly out of the rock this year. And then a deer died next to the fossil. And then there was a flash flood that buried the whole thing. In a few million years, when the flood sediment (dated to Holocene and containing both deer and Triceratops fossils) became exposed, people might think Triceratops survived until the Holocene alongside deer!

[SBell]

This entire issue was discussed to some degree in a previous thread, about the extinction event. Wings posted the published paper regarding the supposed dinosaur remains from the San Juan basin being referenced by this writer.In essence the paper examined the various issues and arrived at the conclusion that in the case of these fossils rather than the seperate bones being reworked, the explanation supported by the sediment layers was that the entire fossil bearing layer had been lifted and transposed over a younger geological layer creating the out of sequence fossil remains.

So really big tectonic reworking!

Not tectonic, just re-buiral. Let's say a Triceratops skeleton eroded mostly out of the rock this year. And then a deer died next to the fossil. And then there was a flash flood that buried the whole thing. In a few million years, when the flood sediment (dated to Holocene and containing both deer and Triceratops fossils) became exposed, people might think Triceratops survived until the Holocene alongside deer!

Generally, geologic layers don't 'shift up' without tectonics.

Although come to think of it, I know of an Eocene site where younger sediments are below the older sediments. We determined that it was likely due to a localized slump (the site is about 200m wide, but the occurrence is only across 1/3 of it). In a case like that, a skeleton--or big pile of bones--being carried in a slump block is a pretty lucky occurrence (not impossible, but very cool!).

[Dinoguy2]

This entire issue was discussed to some degree in a previous thread, about the extinction event. Wings posted the published paper regarding the supposed dinosaur remains from the San Juan basin being referenced by this writer.In essence the paper examined the various issues and arrived at the conclusion that in the case of these fossils rather than the seperate bones being reworked, the explanation supported by the sediment layers was that the entire fossil bearing layer had been lifted and transposed over a younger geological layer creating the out of sequence fossil remains.

So really big tectonic reworking!

Not tectonic, just re-buiral. Let's say a Triceratops skeleton eroded mostly out of the rock this year. And then a deer died next to the fossil. And then there was a flash flood that buried the whole thing. In a few million years, when the flood sediment (dated to Holocene and containing both deer and Triceratops fossils) became exposed, people might think Triceratops survived until the Holocene alongside deer!

Generally, geologic layers don't 'shift up' without tectonics.

Although come to think of it, I know of an Eocene site where younger sediments are below the older sediments. We determined that it was likely due to a localized slump (the site is about 200m wide, but the occurrence is only across 1/3 of it). In a case like that, a skeleton--or big pile of bones--being carried in a slump block is a pretty lucky occurrence (not impossible, but very cool!).

There are also areas of the Hell Creek formation where Cretaceous and Paleogene fossils are mixed together due to Paleocene rivers cutting down into Maastrichtian strata and then being filled back in with Paleocene sediment.

[Splonkadumpocus]

This entire issue was discussed to some degree in a previous thread, about the extinction event. Wings posted the published paper regarding the supposed dinosaur remains from the San Juan basin being referenced by this writer.In essence the paper examined the various issues and arrived at the conclusion that in the case of these fossils rather than the seperate bones being reworked, the explanation supported by the sediment layers was that the entire fossil bearing layer had been lifted and transposed over a younger geological layer creating the out of sequence fossil remains.

I've examined a site in South Dakota where an Eocene formation was tectonically uplifted to form a large hill. Subsequent weathering events caused parts of it to be redeposited on top of the surrounding Oligocene layers.

So really big tectonic reworking!

Not tectonic, just re-buiral. Let's say a Triceratops skeleton eroded mostly out of the rock this year. And then a deer died next to the fossil. And then there was a flash flood that buried the whole thing. In a few million years, when the flood sediment (dated to Holocene and containing both deer and Triceratops fossils) became exposed, people might think Triceratops survived until the Holocene alongside deer!

Generally, geologic layers don't 'shift up' without tectonics.

Although come to think of it, I know of an Eocene site where younger sediments are below the older sediments. We determined that it was likely due to a localized slump (the site is about 200m wide, but the occurrence is only across 1/3 of it). In a case like that, a skeleton--or big pile of bones--being carried in a slump block is a pretty lucky occurrence (not impossible, but very cool!).

I've worked on a site in South Dakota where an Eocene formation had been uplifted into a big hill by tectonic processes. Parts of it had later slumped down to the point where they were lying on top of the surrounding Oligocene layers.