How the turtle got its unique hard shell (proven Theory/s)

www.bbc.co.uk ^ | 31 May 2013 | Melissa Hogenboom

[kimtom]

(photo in article)

How the turtle shell evolved has puzzled scientists for years, but new research sheds light on how their hard shells were formed.

Scientists say the ancient fossil skeleton of an extinct South African reptile has helped bridge a 30 to 55-million-year gap.

This ancestor of the modern turtle, Eunotosaurus, is thought to be around 260 million years old.

It had significant differences to a recently found fossil relative.

Eunotosaurus was discovered over a century ago but new research in the journal Current Biology has only now analysed its differences to other turtle fossils.

Eunotosaurus africanus Skeleton An extinct reptile fossil has helped scientists discover how turtles hard shells are formed A turtle's shell is unique in that it is made up of around 50 bones, with ribs, shoulder bones and vertebrae fused together to form a hard external shell.

How it forms today can be observed in a developing turtle embryo. Ribs broaden first followed by the broadening of vertebrae. The final state is the development of an outer layer of skin on the perimeter of the shell.

"The turtle shell is a complex structure whose initial transformations started over 260 million years ago in the Permian period," said lead author of the study, Dr Tyler Lyson from the Smithsonian Institution and Yale University .........

[SWAMPSNIPER]

When my daughter was in grade school we got into rescuing Box Tortoises that got damaged crossing roads. If they weren't cracked too bad they often healed right up with a little TLC.

That plan turned into a back yard full of Box Tortoise nests and a whole lot of babies to relocate every year.

They lay eggs and the eggs hatch exactly in cycle with the marine turtles, if you see a Box Tortoise digging a nest you can bet that her salt water cousins are doing the same.

A few hung around for years and would charge up at full tortoise speed for a bite of hamburger and a head rub.

They are in decline now, suburban yards are just too neat and tidy to make good habitat, for anything, actually.

[TheOldLady]

Beautiful! I’ve seen a similar arrangement of deceased tree in the water with turtles on it.

Bryan and I saw it when we were hiking at Hinkley Lake in Ohio.

They were too far off to get the perfect picture that you took, but we still enjoyed seeing them.

[SWAMPSNIPER]

Sooner or later some damned fool will come along, drag that dead tree out of the pond, and claim to be making things better.

[TheOldLady]

It would have to be a liberal. Just can’t leave well enough alone.

[raybbr]

[SWAMPSNIPER]