The oldest fossils of animal footprints ever found on land might change the current thought by proving that critters beat plants out of the primordial seas. Lobster-sized, centipede-like animals made the prints wading out of the ocean and over sand dunes about 530 million years ago. Previous fossil animal tracks were 490 million years old.

Simon Braddy of the University of Bristol, UK. and a team of Canadian and British researchers found about 25 rows of foot prints left by many-legged animals, preserved in rocks in south- eastern Canada. They know it to be 'land' prints because ripples and fine layering in the sandstone are characteristic of wind-blown sand rather than underwater sediments.

The footprints in each track are 4-5" apart (8-10cm) apart and indicate the animals were about 25" long (50 cm), and had 16-22 legs. A groove in between the tracks means they also dragged a tail behind them. It is most unlikely that the creatures lived on land and came ashore to mate and lay eggs, as horseshoe crabs and sea turtles do today. The multiple fossil tracks are of different widths, meaning that the ancient dunes were well trodden.

 

Tracks in the Australian desert may be of the oldest multi-celled organisms. The  grooves may have been made by creatures similar to worms which were crawling  around one billion years ago. Another theory is that groups of single-celled  creatures moving together could have also been responsible.

The snail-like tracks are about one millimeter wide and several centimetres long.   Experts think whatever made the marks probably died out in an evolutionary dead-end and never evolved to be any modern day critter. They seem to have moved on a slime-like cushion which preserved the grooves. Yuck.

 Paleontologist Stefan Bengtson, of the Swedish Museum of Natural History, says the  sandstone bearing the tracks is at least 1.2 billion years old, possibly as much as 2  billion - but says the lower end of the time range makes more "biological sense":