soft tissue fossils

22 Jul 2015

At http://phys.org/print356593679.html ... apparently, soft tissue is often preserved in fossils - such as worm sperm from Antarctica (80 million years ago). Such worms reproduce by releasing their eggs and sperm and weave it into protective cocoons - and it is this that kept it intact in what are shallow marine gravels.

A tiny ostrocod, or seed shrimp, was found in Silurian rocks on the Welsh borders - preserved in 3 dimensions with all its soft tissue fossilised. Apparently, it was smothered and petrified in volcanic ash 400 million years ago.

Coprolites, once a thriving extraction industry in some parts of southern Britain, is basically made of petrified dinosaur dung - and it was used as a fertiliser. Bromolites are also excretia and can be found in all manner of rocks from all manner of long agos. In Australia the dung of pleisosaurs have revealed these marine creatures were bottom feeders.

In Jurassic shales (near Peterborough and Whitby for example) pavements made literally from squid like animals known as belemnites have been found - so many of them bunched together they defy explanation. One interpretation on offer is they are the vomit of ichthyosaurs.

Fossilised dung of hyenas were found in Kirkdale Cave in North Yorkshire in the early 19th century, in what is really a cliffside hollow which was full of large mammal bones. These included elephants and rhinoceros and the bones were said to show signs of being gnawed at. William Buckland, a famous geologist of the period, and who happened to have a pet hyena, claimed the dung came from them (as hyena bones were also found in the assemblage). He recognised it as hyena dung - it had to come from an animal so that is not being questioned. It is the idea the bones were gnawed at - indicating Buckland thought the bones had been heaped up in the cave, or hollow, prior to the hyena getting at them with its teeth. Whilst that is not impossible - it may however be quite the wrong interpretation if elephants, rhinoceros, hyean and other exotic fauna had all been entombed at the same time. The dung could have been in the hollow prior to the deposit of the bones - and it could have been a hyena den as observed by Buckland.

What is remarkable, also, is that just 120,000 years ago, during the last interglacial period, exotic fauna that we nowadays associate with Africa, was living in the Vale of Pickering. What happened to switch the climate from exotic (savannah) to temperate - or the cold weather of last the Ice Age? We can only guess.