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| PALEOCENE DINOS? |
| 2009-04-29 |
| ABSTRACT Dinosaur fossils are present in the Paleocene Ojo Alamo Sandstone and Animas Formation in the San Juan Basin, New Mexico, and Colorado. Evidence for the Paleocene age of the Ojo Alamo Sandstone includes palynologic and paleomagnetic data. Palynologic data indicate that the entire Ojo Alamo Sandstone, including the lower dinosaur-bearing part, is Paleocene in age. All of the palynomorph-productive rock samples collected from the Ojo Alamo Sandstone at multiple localities lacked Cretaceous index palynomorphs (except for rare, reworked specimens) and produced Paleocene index palynomorphs. Paleocene palynomorphs have been identified stratigraphically below dinosaur fossils at two separate localities in the Ojo Alamo Sandstone in the central and southern parts of the basin. The Animas Formation in the Colorado part of the basin also contains dinosaur fossils, and its Paleocene age has been established based on fossil leaves and palynology. Magnetostratigraphy provides independent evidence for the Paleocene age of the Ojo Alamo Sandstone and its dinosaur-bearing beds. Normal-polarity magnetochron C29n (early Paleocene) has been identified in the Ojo Alamo Sandstone at six localities in the southern part of the San Juan Basin. An assemblage of 34 skeletal elements from a single hadrosaur, found in the Ojo Alamo Sandstone in the southern San Juan Basin, provided conclusive evidence that this assemblage could not have been reworked from underlying Cretaceous strata. In addition, geochemical studies of 15 vertebrate bones from the Paleocene Ojo Alamo Sandstone and 15 bone samples from the underlying Kirtland Formation of Late Cretaceous (Campanian) age show that each sample suite contained distinctly different abundances of uranium and rare-earth elements, indicating that the bones were mineralized in place soon after burial, and that none of the Paleocene dinosaur bones analyzed had been reworked. |
| Posted by:3dc |
| #14 Recently, there is possible evidence of a Dead Clade Walking: in 2001, evidence was presented that pollen samples recovered near a fossilized hadrosaur femur recovered in the Ojo Alamo Sandstone at the San Juan River indicate that the animal lived in Tertiary times, approximately 64.5 million years ago or about 1 million years after the K-T event.[2] Many scientists, however, dismiss the "Paleocene dinosaurs" as re-worked, i.e. washed out of their original locations and then re-buried in much later sediments.[3] A compelling argument against re-working would be a complete or at least associated skeleton (e.g. more than one bone from the same individual) found above the K-T boundary. As yet no such finds have been reported. |
| Posted by: john frum 2009-04-29 21:22 |
| #13 The Lazarus Dinosaurs of James Fassett |
| Posted by: john frum 2009-04-29 21:18 |
| #12 Now anyone who's been reading the papers lately know, for a fact, that it was Swine Flu which killed the Dinosaurs! No it was the Chimpy McBush-Cheny Flu that did it when the Dinosaurs refused to give us all their oil for 24 beads of costume jewelery. |
| Posted by: One Eyed Ebbereting5067 2009-04-29 20:32 |
| #11 I seem to recall some speculation that a meteor impact might have triggered a cascade of plate tectonic movements and volcanic eruptions - possibly even the millenia-long flood basalts. |
| Posted by: Glenmore 2009-04-29 19:54 |
| #10 Flood basalts aren't like a normal volcanic eruption. They are a series of multiple eruptions of basaltic or oceanic magma that can occur during the rifting process. The flood basalt in question, occured around 68 million years ago in west and central India. It's called the Deccan Traps. It covered 1,500,000 km2 with around 2,000m thick beds of lava. Not exactly you're typical eruption. Volume wise you're looking at around 3 million cubic kilometers of rock. For contrast, the last full eruption of the Yellowstone Caldera managed to eject about 1000km3. As you can see, the scale is different by several orders of magnitude. |
| Posted by: Silentbrick 2009-04-29 18:45 |
| #9 Now anyone who's been reading the papers lately know, for a fact, that it was Swine Flu which killed the Dinosaurs! |
| Posted by: CrazyFool 2009-04-29 18:38 |
| #8 Shoulda, coulda, woulda. There is no perfect to include wiping out the entire population of dinosaurs. Let's remember that presently science traces birds back to them. That means somehow some of them made it through. Crocodiles are believed to be 200 million years old whereas dinosaurs suffered a mass extinction 65 million years ago. So what we see as with other extinction events is a large population drop off which allow other species opportunities to exploit that they previously couldn't because they didn't have the presence to compete, along with radical environmental changes that did not favor species that were optimized in the pre-cataclysmic environment. That some make it for a while beyond the major event isn't unreasonable. The point about the Mammoth is applicable with the last surviving elements estimated to have survived until 1,650 BC on Wrangel Island. |
| Posted by: Procopius2k 2009-04-29 18:35 |
| #7 Thrown up against these theories is the very plausible notion that the bioload of prions and virii had built up in dinosaurs to such an extent that they were already on their way out when the meteor struck, administering what was a coup de grace on an already moribund clade of animals. There is plenty of evidence to support this theory, albeit much of it indirect. The most compelling is that the number of different species of dinosaurs had been decreasing rapidly for more than a million years before the KT strike, and this without a concomitant increase in mammal fossils. Could some dinosaur species have existed in small numbers and widely scattered populations after the KT evenT? It could have happened, there is a modern precedent. Mammoths existed for a very long time after their numbers were big, on a few islands scattered around the northern hemisphere where there was little chance of human predation and outside diseases reaching them, right up until two or three thousand years ago (into historical times). In fact, many legends of giant monsters in Greek, Egyptian, pre-Celtic, and American Indian mythos may be based originally upon actual encounters with live mammoths. |
| Posted by: no mo uro 2009-04-29 18:12 |
| #6 OK silentbrick, I thought much the same (poison Gasses), so which volcano blew around that time? |
| Posted by: Redneck Jim 2009-04-29 17:47 |
| #5 The meteor idea is quite popular, and like many things that are popular, its not got alot of scientific backing really. The more likely killer is flood basalts, which is essentially a massive scale volcanic eruption that goes on for well, could be a few million years, throwing megatons of dust, sulfur dioxide and other gases into the air. Matching flood basalt events to mass extinctions doesn't have perfect correlation, but it's pretty close. |
| Posted by: Silentbrick 2009-04-29 17:11 |
| #4 I'm not going to pretend I know squat about geology. Having said that , just when exactly did Yellowstone last erupt? |
| Posted by: Redneck Jim 2009-04-29 17:08 |
| #3 Now now now, history and natgeo have been telling me the last month that it was not a meteor but climate change which killed the dinosaurs - which means industrialists killed the dinosaurs. Granted, a meteor strike would cause a bit of climate change, but then why not use fallout instead of turning the program into a binge drinking game so foul you can hear pee-wee herman screaming the secret word 'Climate Change' halfway through the show. An interesting find. |
| Posted by: swksvolFF 2009-04-29 16:41 |
| #2 This is news because dinosaurs shouldn't be in the Paleocene. The Paleocene is the 10 million year period following the Cretaceous. The K-T boundary, which marks the end of the K (for Cretaceous) era and the beginning of the T (for Tertiary) era. Thus this piece of evidence goes against the current consensus 'big meteor wiped out dinos' hypothesis. |
| Posted by: lord garth 2009-04-29 14:34 |
| #1 So? The Paleos have been acting like pre-historic beasts for a long time, why is this news? |
| Posted by: AlanC 2009-04-29 14:15 |