Post reply

Reply to the message by David Turell

Name:

E-mail: (optional, won't be displayed directly)

Leave this field empty:

Homepage: (optional)

Leave this field empty:

Location: (optional)

Remember me (cookie)

Category:

Subject:

Formatting help

skip to input

format text bold: [b]bold text[/b]
format text italic: [i]italic text[/i]
insert hyperlink: [link=http://example.com/]link text[/link] / [link]http://example.com/[/link]
set text color: [color=#rgb]colored text[/color]
font size: [size=small]small text[/size]; [size=large]large text[/size]
insert list: [list][*]list item[/list]
insert image: [img]http://example.com/image.jpg[/img]; left: [img=left]http://example.com/image.jpg[/img]; right: [img=right]http://example.com/image.jpg[/img]; thumbnail: [img=thumbnail]http://example.com/image.jpg[/img]; thumbnail left: [img=thumbnail-left]http://example.com/image.jpg[/img]; thumbnail right: [img=thumbnail-right]http://example.com/image.jpg[/img]

:-)
;-)
:-P
:-D
:-|
:-(

Message:

> Of vertebrate footprints  313 million years ago:
> 
> https://www.sciencedaily.com/releases/2020/08/200821120756.htm
> 
> "Paleontological research has confirmed a series of recently discovered fossils tracks are the oldest recorded tracks of their kind to date within Grand Canyon National Park. In 2016, Norwegian geology professor, Allan Krill, was hiking with his students when he made a surprising discovery. Lying next to the trail, in plain view of the many hikers, was a boulder containing conspicuous fossil footprints.
> 
> ***
> 
> "'These are by far the oldest vertebrate tracks in Grand Canyon, which is known for its abundant fossil tracks" says Rowland. "More significantly," he added, "they are among the oldest tracks on Earth of shelled-egg-laying animals, such as reptiles, and the earliest evidence of vertebrate animals walking in sand dunes."
> 
> "The track-bearing boulder fell from a nearby cliff-exposure of the Manakacha Formation. The presence of a detailed geologic map of the strata along the Bright Angel Trail, together with previous studies of the age of the Manakacha Formation, allowed the researchers to pin down the age of the tracks quite precisely to 313 +/- 0. 5 million years.
> 
> "The researchers' reconstruction of this animal's footfall sequence reveals a distinctive gait called a lateral-sequence walk, in which the legs on one side of the animal move in succession, the rear leg followed by the foreleg, alternating with the movement of the two legs on the opposite side. "Living species of tetrapods―dogs and cats, for example―routinely use a lateral-sequence gait when they walk slowly," says Rowland. "The Bright Angel Trail tracks document the use of this gait very early in the history of vertebrate animals. We previously had no information about that." Also revealed by the trackways is the earliest-known utilization of sand dunes by vertebrate animals."
> 
> Comment: The canyon is filled with fossils. I made several trips there , hiked Bright Angel four times, the last with my wife Susan. I've not only learned to identify many layers , was shown 200  million year old worm borings by our geologist guide. These tracks are from pre-primate animals