Paleocene dinosaurs

Paleocene dinosaurs describe families or genera of non-avian dinosaurs that may have survived the Cretaceous–Tertiary extinction event 65.5 million years ago. Although almost all evidence indicates that dinosaurs (other than birds) all went extinct at the K-T boundary, there is some scattered evidence that these non-avian dinosaurs lived for a short period of time during the Paleocene epoch. The evidence for Paleocene dinosaurs is rare and remains controversial.

Evidence

Several researchers have stated that some dinosaurs survived into the Paleocene and therefore the extinction of dinosaurs was gradual. Their arguments were based on the finding of dinosaur remains in the Hell Creek Formation up to 1.3 metres above (40,000 years later than) the K-T boundary. Similar reports have come from other parts of the world, including China.[1]

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]

Analysis

Footnotes

1. ^ Sloan, R. E., Rigby, K,. Van Valen, L. M., Gabriel, Diane (1986). "Gradual dinosaur extinction and simultaneous ungulate radiation in the Hell Creek formation". Science 232 (4750): 629-633. DOI:10.1126/science.232.4750.629.. Retrieved on 2007-05-18. 
2. ^ Fassett, JE, Lucas, SG, Zielinski, RA, and Budahn, JR (2001). "Compelling new evidence for Paleocene dinosaurs in the Ojo Alamo Sandstone, San Juan Basin, New Mexico and Colorado, USA". Catastrophic events and mass extinctions, Lunar and Planetary Contribution 1053: 45-46. Retrieved on 2007-05-18. 
3. ^ Sullivan, RM (2003). "No Paleocene dinosaurs in the San Juan Basin, New Mexico". Geological Society of America Abstracts with Programs 35 (5): 15. Retrieved on 2007-07-02. 
The Paleocene, "early dawn of the recent", is a geologic epoch that lasted from 65.5 ± 0.3 Ma to 55.8 ± 0.2 Ma (million years ago). It is the first epoch of the Palaeogene Period in the modern Cenozoic era.
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Dinosauria *
Owen, 1842

Orders & Suborders
  • Ornithischia
  • Cerapoda
  • Thyreophora
  • Saurischia

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Aves
Linnaeus, 1758

Orders

About two dozen - see section below

Birds (class Aves) are bipedal, warm-blooded, egg-laying vertebrate animals.
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Depending on context, epoch can refer to:

Period of time

  • a distinctive historical period or era
  • a unit of the geologic time scale, less than a period and greater than an age
  • a phase in the development of the universe with distinctive properties


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The Paleocene, "early dawn of the recent", is a geologic epoch that lasted from 65.5 ± 0.3 Ma to 55.8 ± 0.2 Ma (million years ago). It is the first epoch of the Palaeogene Period in the modern Cenozoic era.
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The Hell Creek Formation is an intensely-studied division of Upper Cretaceous to lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana.
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The phrase Dead Clade Walking refers to the fact that some clades (groups) of organisms which survive mass extinctions either become extinct a few million years after the mass extinction or fail to recover in numbers and diversity.
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Hadrosauridae
Cope, 1869

Subfamilies
  • Hadrosaurinae Cope, 1869
  • Lambeosaurinae Parks, 1923
Synonyms
  • Trachodontidae Lydekker, 1888
  • Saurolophidae Brown, 1914
  • Lambeosauridae Parks, 1923 vide Horner, 1990

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The femur or thigh bone is the longest, most voluminous, and strongest bone of mammalian bodies. It forms part of the hip and part of the knee.

The word femur is Latin for thigh.
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San Juan River is a tributary of the Colorado River, 400 mi (644 km) long,[1] in the western United States.

Location

It rises in southern Colorado, along the southern slope the San Juan Mountains to the west of the continental divide in southwestern Colorado,
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Tertiary geological time interval covers roughly the time span between the demise of the non-avian dinosaurs and beginning of the most recent Ice Age, approximately 65 million to 1.8 million years ago.
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digital object identifier (or DOI) is a permanent identifier given to a document, which is not related to its current location. A typical use of a DOI is to give a scientific paper or article a unique identifying number that can be used by anyone to locate details of the paper, and
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