Karoo Fossils EarthCache

To complete this Earthcache you will have to visit the Karoo National Park near Beaufort West in the Western Cape, South Africa.

For updated information on Karoo National Park visit the SA National Parks website.

The published coordinates will take you to the start of the Fossil Trail situated a short walking distance from the Reception area of the rest camp. The 300m trail has a paved walkway and is wheelchair accessible.


Karoo Fossils

255 million years ago, in the Late Permian Period, all the major continents were grouped together into a single supercontinent called PANGAEA. This vast landmass stretched from pole to pole across several different climatic belts, from hot equatorial deserts through cool temperate regions to icy poles.

The southern portion of Pangaea is known as GONDWANA. This region was formed by the present-day southern continents of Africa, South America, Australia and Antarctica, as well as India and the Middle East. The KAROO BASIN was a large, landlocked region lying deep within Pangaea. It was isolated from the ocean by a major mountain range. Late Permian climates were therefore semi-arid with well-marked summer and winter seasons.

"In terms of its fossils, the Karoo sequence has been described as one of the great natural wonders of the world. For 50 million years, from 240 to 190 million years ago, a regime of quiet sedimentation persisted almost unbroken, with practically no removal of material, at a time when life on land was young and with the whole Gondwana supercontinent to fill. Think of it as a unique window of evolutionary opportunity, a continuum practically without equal throughout time and around the globe. Fifty million years of continuous fossil record was created and preserved. Now the different levels are presented at the surface, well exposed and easily accessible, reflecting different time periods.

From just above the glacial tillites to almost the highest sandstone below the basalt that cap the Drakensberg, spanning nearly the entire thickness of the sedimentary Karoo sequence, the sediments are fossil-bearing, with plants, invertebrates, fishes and, most importantly, reptiles. Although the Karoo reptiles include the most celebrated of all fossils, the dinosaurs, in these parts they are outranked by another group – a group that filled a vital evolutionary niche, the family called Therapsida, representing a transitional stage between reptiles and mammals.

Struthiocephalus, Bradysaurus and a host of other mammal-like reptiles dominated the plains of Gondwana long before the arrival of the dinosaurs. Later, Tyrannosaurus was to rule half the world, and Massospondylus and his bigger cousin Melanorosaurus – both vegetarian dinosaurs – roamed the Triassic veld of central Gondwana. But the mammal-like reptiles were the ancestors of the order that was to succeed the dinosaurs at the end of the Cretaceous Era, and still has dominion today – the mammals. Dozens of species of mammal-like reptiles have been collected from the Karoo, some big, some small, some vegetarian, some fiercely predatory, short tailed, long tailed, beak-mouthed with tusks, robust or delicate, smooth backed or carrying high, sail-like crests from neck to tail, solitary or gregarious.

This group provides the link between two of the most important groupings in the vertebrates of the animal kingdom today. This form of life was transitional, bridging the gap between egg-laying reptiles and mammals that gave birth to live young. They were skeletally intermediate – showing features of both reptilian and mammalian skeletons. An iguana and an otter might look structurally related, but their skeletons, and particularly their skulls, are quite different, reflecting their divergent evolution and particular lifestyles. And it is not just that the mammal-like reptiles lie somewhere in the gap between early reptiles and mammals: they fill the gap. In other words, within the Therapsida family, there is a steady progression from more truly reptilian in the lower sediments of the Beaufort Group, to more mammal-like fossils in the Stormberg sandstones far above them." Quoted from Geological Journeys p116 - see reference.

EarthCaches are a special type of Virtual Cache that are meant to be educational. Therefore, to log, you must demonstrate that you learned something from the site and experience.

1.) At the waypoint ROCKS1 (S32 19.983 E22 29.863) you will find a display case with rock samples. Briefly explain what caused the distinct patterns seen on Rocks E, B & D. The information board nearby have the answers.