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800px-Mary_Anning_painting

Happy Birthday to Mary Anning (21 May 1799 – 9 March 1847).  Mary’s life was a difficult one.  Her father was a poor cabinet-maker in Lyme Regis (a coastal town in Dorset, England) who supplemented his income by selling strange petrified shells and stone bullets which he pried out of a nearby sea cliff.  Mary’s parents had ten children, but only Mary and her brother survived past early childhood.  Her name was a hand-me-down from an older sister who had burned to death at the age of four.  When Mary was 15 months old, she and three neighbors were under a tree when it was struck by lightning and only Mary survived.  Her father died while Mary and her brother were young and they kept the family afloat by selling curiosities pried from the sea cliffs.  This was dangerous business: Mary’s beloved terrier Tray was crushed in a rockslide (he’s up there sleeping with the ammonites in the painting) and Mary narrowly avoided this fate herself on multiple occasions.  Additionally, living so close to the sea carried further perils: the family nearly drowned from a flood during a great storm.  Mary Anning died of breast cancer at the age of 47.  Her final years were marked by agonizing pain from the condition which she self-treated with laudanum (which caused the community to gossip about her morals).

This is a pretty bleak biography (although in no way atypical for a working-class woman from early industrial Great Britain).  So why are we writing about Mary 172 years after her death anyway? Mary Anning was a great pioneer of paleontology, geology, ichthyology, ecology, and invertebrate zoology.  The luminaries of the English geology community relied on her indomitable fieldwork to frame their conclusions about the history of living things and to stock their museums with specimens. Mary was a religious dissenter and the daughter of a cabinet-maker in an age when geology was the near-exclusive preserve of well-to-do Anglican gentlefolk (the Geological Society of London did not even allow women to attend meetings as guests).  Yet she kept informed of the scientific literature of her day and she dissected fish and invertebrates as to better understand the nature of her excavations and discoveries. Above all, Mary Anning actually discovered the fossils which others wrote about–so she had insights and knowledge which were occluded from armchair scholars. Charles Lyell (the father of geology) wrote to her asking her opinions about cliff erosion.  Mary proposed a theory to William Buckland that some of the fossils she discovered were ingested by ichthyosaurs and the remains excreted (a concept which fascinated Buckland and became the central focus of his work). In a fair world she would have an alphabet of letters after her name and be immortalized as a statue on a plinth beside the statues of Darwin and Lyell.  Even in our fallen world, she is revered as one of the founders of the natural history and life science disciplines (although many biographies about her concentrate on the sad exigencies of her life rather than on the extraordinary discoveries she made, a tradition which I have somewhat followed).

The cliffs which Mary relied on for specimens were part of a geological formation known as the Blue Lias. These layers of limestone and shale were a shallow seabed of the Tethys Ocean during the Jurassic period (about 210–195 million years ago).  The curlicues and stone bullets were fossil ammonites and belemnites, but Mary had a knack for finding the much rarer remains of hitherto unknown creatures such as ichthyosaurs, pterosaurs, plesiosaurs and other ancient marine fauna.

In the early 19th century a debate was raging between learned churchmen who knew for certain that God’s perfect creation could never be diminished and gentlemen geologists who believed that there had once been animals which were gone from earth…”extinct” as they called this new concept.   Mary’s fossils of bizarre giant sea crocodiles and lizard dolphins gave concrete evidence to the ur-paleontologists (who were indeed proven right).  Her discoveries were seminal for the discovery of paleontology itself and paved the way to the understanding that the world’s ecosystems were once very different indeed from what they are like now.   These pieces of knowledge helped towards an understanding of the true age of the Earth and ultimately made Darwin’s discoveries possible.

jurassicmary

Here is another painting of Mary, by the greatest living fish-artist, Ray Troll.  Troll shows Mary with fleshed-out versions of the creatures she discovered (note the ichthyosaur swallowing an ammonite).  We owe an enormous debt to Mary Anning.  Her contributions were under-appreciated in her day (when only the most learned gentleman scientists…and Mary… had inklings of the real nature of natural history and what her super sea-monsters connoted ), but those discoveries undergird our understanding the nature of the planet and of life itself.

 

An artist's depiction of a belemnite

This blog has already traveled back 400+ million years to the Ordovician, the era when great mollusks ruled earth’s oceans. The Ordovician ended in ice as Gondwanaland drifted into the Southern Polar regions—a tectonic shift which brought massive terminal cooling to the great reef systems of the time (and also fundamentally changed Earth’s climate and atmosphere), but the cephalopods were hardly done for.  They continued to evolve and adapt to the world’s ever changing oceans.  Today we pick up the cephalopod story hundreds of millions of years later during the Mesozoic era—the time of dinosaurs.

Artist's depiction of a belemnite school

The reefs and oceans of the Jurassic and Cretaceous were filled with nautiloid cephalopods—ram shelled descendants of the shelled tentacled monstrosities  from the Ordovician—but a new cephalopod had also evolved and filled up the shallow limestone seas in giant teaming schools.  These were the belemnites which lacked an external shell and superficially resembled squid.

Belemnites were distinct from today’s squids for several reasons.  Not only did they possess hard internal shells/skeletons composed of calcium carbonate but they also lacked the pair of specialized hunting tentacles present in modern cuttlefish and squid.  Instead the belemnites hunted with ten arms covered in tiny wicked hooks.

An Amzaingly well preserved fossil belemnite from the 155 million year old Jurassic Solnhofen limestones in Germany (notice the details of the animal's soft anatomy)

Belemnites fed on ostracods, crustaceans, and fish.  In turn they made up a sizeable portion of diet for, well, the sizeable predators of the time.  Fossils of plesiosaurs, pliosaurs, and giant sharks have been discovered with stomachs full of hooks or rostra. It is also thought that the dolphin-like ichthyosaurs survived largely on belemnites.  After feeding and digesting the mollusks, the ichthyosaurs probably vomited out the indigestible hooks and rostra of belemnites much in the manner that sperm whales expel the hooks of giant squid!

The bullet shaped rostra of belemnites have survived in vast numbers and are one of the most characteristic of all Mesozoic fossils.  These strange tapered cones weathered out of soft chalks nearly intact and proved extremely puzzling to people of past generations.  Numerous magical common names and magical folk beliefs grew out of the conical rocks. The English called the fossils “thunderbolts” and believed they were the physical leftovers from lightning strikes.  The ancient Scandinavians thought that belemnite rostra were candles dropped by gnomes, elves, and dwarves on the occasions they traveled from their realms through this world.  The ancient Chinese called them “sword stones” and believed they were imbued with ancient healing magic.

An opalized fossil of a belemnite rostrum

The end of belemnites was even more astonishing than these myths.  The creatures had short lives—which involved a larval phase drifting amidst the microscopic plankton.  The immense extraterrestrial bolide which struck the Earth at the end of the Cretaceous ended the dinosaurs and also finished off the belemnites. The little larvae were unable to survive the massive planktonic die-off which accompanied the long dark winter following the strike.  Fortunately other cephalopods proved hardier–and the most intelligent mollusks continued to change and adapt right up until today.

An artist's depiction of the Chickzalub bolide impact

Leedsichthys problematicus (in the background) being harrassed by a plesiosaur; painting by Dmitry Bogdanov

Leedsichthys (Leedsichthys problematicus) was the largest known bony fish.  It lived during the middle Jurassic (155 million years ago), feeding on algae, plankton, and small shrimp & fish—much like a modern whale shark or baleen whale.  Leedsichthys had over 40,000 teeth with which to skim its meal from the water.  Although most of these huge fish were around 12 meters (approximately 40 feet) or smaller in length, many scientists believe that Leedsichthys was capable of growing much larger.  Fragmentary specimens suggest they attained lengths greater than 17 meters (about 55 feet) and even larger individuals might be found.

Painting by Dmitry Bogdanov

Leedsichthys is named after Alfred Nicholson Leeds, who discovered its fossilized remains in 1886 in England.  He had so much trouble piecing the bones together that he gave the fish the species name of “problematicus”.  Leedsicthys was most likely a global species with a presence in all of the open oceans of the Jurassic world.  It is unclear why the species went extinct, but paleontologists have speculated that it was out-competed by the teleosts–the modern bony fish–which lay vastly more eggs than pachycormids like Leedsichthys.

The world 155 million years ago. No Atlantic Ocean!

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