Fossils have richer stories to tell – about the lub-dub of dinosaur life – than we have been willing to listen to.
Robert T. Bakker
From trilobites to tyrannosaurs, most fossils are of creatures with hard shells or bones. These materials don’t easily biodegrade and sediment has time to build up around them and turn them into a record of the creature that is still with us millions of years after it has died. Soft-bodied organisms like worms, on the other hand, decay rapidly and their fossil record is decidedly patchy.
In exceptional circumstances, however, their remains are preserved and sometimes in the most unusual places. With the right detective skills, paleontologists can use such discoveries to open up whole new windows on the history of life on Earth. A recent discovery found in 50-million-year-old rocks from Antarctica has yielded a particularly incredible example: fossilized worm sperm.
It’s a great reminder that there are far stranger fossils out there than dinosaur bones. Here are some of the most bizarre specimens ever found.
1 – Ancient Sperm – 50-million-year-old fossilized spermatozoa
A fossil of a sperm is beyond anyone’s imagination. But, the researchers found a remarkable 50-million-year-old fossilized spermatozoa from a clitellate or “collared”. It represents the oldest animal sperm ever discovered, beating the previous records. It was found in the shallow marine gravels on the Antarctic Peninsula, the scientists believe that the preservation of this sperm was made possible because such worms reproduce by releasing their eggs and sperm into protective cocoons. Using a high power lens, the sperm was studied and it resembled those of a leech-like group of worms that attach themselves to crayfish.
2 – A well-Endowed 425 million-year-old Silurian Shrimp
Discovered in a ditch near the Anglo-Welsh border in the early 2000s, a fossilized ostracod, or seed shrimp, proved to be quite clearly male. Preserved in three dimensions with all its soft tissues fossilized, it was proportionally well-endowed. “Old Todger” was the headline in the The Sunnewspaper.
During the Silurian period (443-419 million years ago), the Welsh borderlands lay on the shelf of a tropical sea. Marine animals were occasionally smothered, entombed and petrified by the ash of distant volcanoes. The ostracod – and countless other small fossils – cannot be seen adequately using microscopes, however, so their mineral tomb has to be gradually ground away and the fossil recreated with 3-D digital imaging.
3 – Dinosaur Poo
You have heard a lot about Dinosaur fossils, but have you ever heard about the fossilised Dinosaur’s poo? Apart from being the most wanted found in many paleontological shops, the poo fossils are an excellent resource for scientists to study what the extinct were feeding on. Coprolites, was a term coined in the early 1990s to encompass all matter of excreta preserved in the rock record.
“In Australia, they show that Cretaceous plesiosaurs were bottom feeders. In Poland the regurgitated dinners of shell-crushing fish help us work out how life recovered from the biggest mass extinction in Earth history. And in Jurassic shales from Peterborough and Whitby, pavements of squid-like belemnites have been interpreted as ichthyosaur vomit.” – as found in discoverymagazine.com
4 – English Rhinos
One very odd fossil discovery was made in Kirkdale Cave in the UK in 1821. Workman quarrying for roadstone found a cliffside hollow full of large animal bones. They were at first thought to be cattle, but a local naturalist saw that they were more exotic-looking, and the remains eventually made their way to Oxford University’s Professor William Buckland.
A man who claimed to have eaten his way through the entire animal kingdom, Buckland was the most marvelous experimental scientist. He recognized that the bones were mainly of large herbivores, such as elephants and rhinos. They showed signs of having been gnawed, and fossilized feces found on the cave floor resembled those of hyenas. Conveniently being in possession of one as a pet, Buckland proved Kirkdale Cave had been a hyena den, and founded the science of paleoecology. Almost two hundred years on, we know that “African” megafauna roamed the Yorkshire area about 125,000 years ago, in a warm phase between ice ages.
5 – A Mystery Monster
The fossils of Mazon Creek in Illinois, USA, were first encountered during coal mining in the 19th Century. But it wasn’t until the 1950s that the site became fossiliferously famous, thanks to Francis Tully’s discovery of an exceptionally weird beast: a beautifully preserved soft-bodied animal revealed in a naturally split mineral nodule.
Specimens turned out to be quite abundant but unique to Mazon Creek, and the beast was given the name of Tullimonstrum gregarium. It is now the state fossil of Illinois. Trouble is, no one knows what Mr. Tully’s Common Monster really is. A few inches long, it has a long snout with toothy pincers at the end, two eyes on stalks, a segmented body, and a finned tail. It was probably a predator, and the rocks it was found in suggest that it lived in tropical, shallow seas.
Beyond that, after more than half a century, we’re not much the wiser. It cannot be satisfactorily united with any other invertebrate group, living or extinct. Even with exceptional preservation, the fossil record always has the capacity to surprise.