Fossil find

The "Messel on Tour" exhibition reveals its beauty and significance upon long contemplation of the 125 fossils displayed individually in backlit glass cases. It takes time - and great eyesight - to notice the delicate feather crest on the head of a swift, the fine traces of spines surrounding a hedgehog-like animal, or the tiny fetus of a foal inside the womb of a primeval pygmy horse.

The fossils, part of a special touring exhibition that opened at Stuttgart’s Natural History Museum on Thursday, come from an ancient lake bed located 30 kilometers (19 miles) south of Frankfurt.

Some 48 million years ago, a violent volcanic eruption formed a 300 meter deep crater that filled with water. A plethora of flora and fauna subsequently established itself in and around the freshwater lake.

Tropical paradise

Fossilized plant material, including palm leaves, fruits, wood, and pollen, show the lake was surrounded by a dense subtropical jungle, while the presence of tropical animals such as crocodiles, soft-shelled turtles and tapirs reveal that the climate back then was much warmer and wetter than it is today.

"It was the warmest period on earth (in) the past 70 million years," said paleontologist Dr. Johanna Eder, the director of Stuttgart's Natural History Museum. "The Messel fossils show us the tropical conditions in all of Europe."

Tens of thousands of preserved flora and fauna specimens, from water plants to beetles, birds, snakes, fish and frogs have already been excavated from the 190-meter sediment layer that once formed the bed of the ancient lake. They are the finest preserved examples dating from the Middle Eocene period - between 57 million and 36 million years ago.

The astounding preservation of the Messel Pit fossils allows even wing membranes, insect coloring and stomach contents to be visible, providing a unique insight into the feeding habits, ecology and living environment of the area.

"If you only have the skeleton and ... the teeth, you can only estimate what the animal was feeding on, but if you have the stomach content, then you can really see it," said Eder.

"For example, we had a long discussion concerning the (pygmy) horse, because modern horses (are) feeding on grasses, but we have hardly any grasses in Messel. The stomach content showed clearly that ... these primitive horses were feeding on leaves and also fruit."

Early mammals document evolution

The Messel fossils "uniquely document" the early stages of the evolution of mammals, which first appeared at the start of the Eocene epoch, according to the exhibition curator Dr. Norbert Mickrich from the Hessian Regional Museum in Darmstadt,

"Messel opens a window in the earth's history only a short time after the end of the dinosaurs," he said.

Dinosaurs disappeared from the earth about 65 million years ago, leaving ecological niches free for mammals to develop and diversify.

"Messel documents this vast possibility of ecological radiations," Mickrich said. "For example, if you look at groups (such as the) hedgehog-like mammals, no one expected (them) to be so diverse at this time."

Forty-five species of mammals have been found at Messel, including bats, opossums, a lemur-like monkey, rodents, and a primitive anteater. The excavation of the complete anteater skeleton caused the rewriting of evolutionary history as previously the species was assumed to be restricted to South America.

Prime preservation conditions

The extraordinary preservation of the Messel fossils is a result of a unique set of circumstances. From the abundance of terrestrial vertebrate fossils near the original lake shore, scientists believe poisonous gas emerged periodically from the lake killing these animals.

The lake's lower levels probably lacked oxygen rendering the depths uninhabitable. This meant corpses that sank to the lake's floor lay undisturbed by scavengers.

Seasonal algae blooms would periodically have starved animals living in the upper layers of oxygen, causing them to die and sink to the bottom of the lake. Over a period of a million years, this algae, as well as mud and clay, subsided to the lake bed, preserving the examples of the flora and fauna in an oily shale.

Saved from destruction

The oily Messel shale was mined to make tar and paraffin from the middle of the 19th century until 1971. Although the first fossils were discovered as far back as 1875, it wasn't until the disused mine pit looked liked being turned into a rubbish dump that activists started to push for the site's conservation.

It took 20 years to save the Messel pit, which was finally bought by the Hessian state in the early 1990s. The site was awarded UNESCO World Heritage Listing in 1995.

The "Messel on Tour" exhibition remains on display in Stuttgart until Aug. 30.

Author: Kate Hairsine

Editor: Sean Sinico