Paleocene

Paleocene

The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...

 dinosaur

Dinosaur

Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

s describe families or genera of non-avian

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

 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

Paleocene

The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...

 epoch

Epoch (geology)

An epoch is a subdivision of the geologic timescale based on rock layering. In order, the higher subdivisions are periods, eras and eons. We are currently living in the Holocene epoch...

. The evidence for Paleocene dinosaurs is rare and remains controversial.

Evidence

Several researchers have stated that some dinosaurs survived into the Paleocene

Paleocene

The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...

 and therefore the extinction of dinosaurs was gradual. Their arguments were based on the finding of dinosaur remains in the Hell Creek Formation

Hell Creek Formation

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...

 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.

There is possible evidence of a Dead Clade Walking

Dead Clade Walking

The phrase Dead Clade Walking refers to the fact that some clades of organisms which survived mass extinctions, either become extinct a few million years after the mass extinction or fail to recover in numbers and diversity.-Origin of phrase:...

: in 2001, evidence was presented that pollen samples recovered near a fossilized hadrosaur femur

Femur

The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...

 recovered in the Ojo Alamo Sandstone at the San Juan River indicate that the animal lived in Tertiary

Tertiary

The Tertiary is a deprecated term for a geologic period 65 million to 2.6 million years ago. The Tertiary covered the time span between the superseded Secondary period and the Quaternary...

times, approximately 64.5 million years ago or about 1 million years after the K-T event. Direct dating of bone has also been used to present an age of 64.8 ± 0.9 million years for one specimen. 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. 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.