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An artist’s conception Jurassic ammonites

I have always been fascinated by cephalopods. One of my favorite parts of natural history museums is seeing the reconstructions of ancient oceans where the big gray spirals are re-imagined with the colors and textures (and tentacles) of real life. Those stunning reconstructions and thrilling artworks are based on the appearance and anatomy of modern cephalopods…and pretty much nothing else. The soft tissue of orthocones, ammonites, and belemnites is not preserved in the fossil record. Invertebrate paleontologists (and artists) have been forced to flesh in those fabulous shells with information gleaned from octopuses squids, and nautiluses.

Until now! Scientists looking at limestone “pages” from the the extraordinary Solnhofen-Eichstätt deposits southern Germany were perplexed by a weird ancient blob (above). I hope you will take a moment to look at these seemingly meaningless pink and yellow smudges and smears. Such an examination provides testament to the gifts of paleontologist Christian Klug of the University of Zurich who was able to decipher what this truly is: the body of a 150 million year old ammonite somehow removed from its shell and preserved in an anoxic lagoon.

Through Klug’s reconstructive prowess we are able to gift the anatomy of this ancient creature. Ammonoids were common in Earth’s oceans from the Ordovician until the end of the Cretaceous (a 400 million year run) and they are invaluable to geologists as index fossils, but, in some ways we don’t know much about them. Although this fossil helps us to understand their anatomy, it also engenders new questions. For example, how did this particular mollusk die? It is possible it was ripped from its shell by some Jurassic monster which then lost hold of the morsel. After watching the decaying creatures drifting in the tides of the Chesapeake, however, I am more inclined to think that the interstitial tissues which held the ammonite in its shell decayed and the dead animal slid out. This hypothesis is somewhat supported by what is still missing from this extraordinary find: the arms! Ammonite scientists would dearly love to know about the arms of these creatures. Were they numerous and weak like the arms of nautiluses? Were they long and strong like the grabbing arms of cuttlefish? Did ammonites have different sorts of arms for different purposes? (based on modern cephalopods, this would be my guess). We still don’t know, but the very existence of this fossil shows that with luck, infinite patience, and Professor Klug’s sharp eyes, it is possible to discover things lost for hundreds of millions of years. Maybe there are other finds waiting out there in the ancient rock!

Here is a Cretaceous drama (including both original players) captured in amber and perfectly preserved for 99 million years.  A predatory “hell ant” (haidomyrmecine) was grasping a proto-cockroach (Caputoraptor elegans) in its strange vertical mandibles when a dollop of sap preserved both creatures in resin.  Because it was so well preserved, we can see how the hell ant’s mouth parts are completely different from those of modern ants. Today’s ants all have horizontal side to side scissor-like mandibles.  The ancient hell ant has scythelike vertical mandibles which meet up with horn like appendages on its forehead (like a platybelodon…if its upper tusks came out above its eyes).

hell-ant

The ant was found in a piece of amber from modern Myanmar and gives us a precious window into the lives of ancient ants (which were seemingly as widespread in the age of the dinosaurs as they are now, yet were also completely different than they are now).  The first ants evolved during the Jurassic (170 million years ago) so the hell ant is nearly as far removed from its first ancestors as today’s ants are from it.  Sometimes it seems like the way we picture the world–an empire belonging to dinosaurs, Andrewsarchus, or humans–must be ridiculous to ants.  To them we macrofauna must seem like ludicrous obscene monsters who dwell in a different world and are doomed to disappear in the immediate future (the same as Kardassians appear to us normal people).

Different fossil plants and animals from the lacustrine deposits of the McAbee Flora of the Eocene (British Columbia, Canada)

Different fossil plants and animals from the lacustrine deposits of the McAbee Flora of the Eocene (British Columbia, Canada)

Today we return to the long-vanished summer world of the Eocene (the third epoch of the Cenezoic era). During most of the Eocene, there was no polar ice on Earth: a balmy temperate summer held sway from Antarctica to Svalbard. British Colombia was covered by a tropical rainforest where palm trees and cycads contended with warm weather conifers (and with the ancestors of elms, cherries, maples, and alders). Within this warm diverse forest, which thrived between 55 and 50 million years ago, lived numerous strange magnificent birds and insects. Shoals of tropical fish thronged in the acidic foaming waters (which were practically carbonated—since the atmospheric carbon dioxide levels of the Eocene were probably double that of the present).   The mammals of this lovely bygone forest were equally splendid–strange proto-carnivores not closely related to today’s mammalian predators,  weird lemur analogs, and strange ur-rodents. This week the discovery of two new mammal species was announced.  These remarkable fossil finds provide us with an even better picture of the time and place.

a reconstruction of the early Eocene  in northern British Columbia, a tapir-like creature from the genus heptodon with a while tiny proto-hedgehog in the foreground. (Julius T. Csotonyi)

a reconstruction of the early Eocene in northern British Columbia: a tapir-like creature (genus Heptodon) with a tiny proto-hedgehog in the foreground. (Julius T. Csotonyi)

One of the two creatures discovered was a tapir-like perissodactyl from the genus Heptodon. The newly discover tapir was probably about the size of a large terrier. I really like tapirs (and their close relatives) but these remains are not a huge surprise–since many perissodactyls thrived in North America during the Eocene. The other fossil which paleontologists found is a surprise—an adorable surprise! Within a stone within a coal seam was a tiny jaw the size of a fingernail. Such a fossil would have been all but impossible to study in the past, but the paleontological team led by David Greenwood, sent the little fossil to be scanned by a CT scanner and then imaged with a 3D scanner. The tiny jaw was from a diminutive hedgehog relative since named Silvacola acares.  The little hedgehog grew to a maximum adult size of about 6 cm (2.3 inches) long or approximately thumb-sized. Since it probably lacked spines, this miniature hedgehog was a bit different than the modern hedgehog, but it was definitely a relative.

As discussed in previous posts, I like to imagine the balmy Eocene, when so many mammals which are now the mainstay of our familiar Holocene/Anthropocene world got their first start. It makes it even better to imagine that the thickets were filled with endearing hedgehogs the size of bumble bees.

Rodhocetus (by Pavel Riha)

Rodhocetus (by Pavel Riha)

This endearing beasty is Rodhocetus, a long extinct proto-whale which lived during the mid-Eocene (approximately 40 to 50 million years ago). Rhodhocetus fossils are found in contemporary Pakistan, but the world has changed greatly since the warm Eocene: the creatures did not live on the tops of mountains, but rather in estuaries and shallow seas.

Rodhocetus

Rodhocetus

The early cetaceans shared ancestors with the artiodactyls (cows, pigs, hippos, goats, and suchlike even-toed ungulates) and indeed the first cetaceans, from the beginning of the Eocene, look somewhat like weird squashed hippos or water cows. By the middle of the epoch, however the familial similarities were beginning to fade.

06-14-P-02-G-01-KlausmeyerRodhocetus-full_1

Rodhocetus specimens have elongated hands and feet–which were almost certainly webbed. Their hipbones were not fused to their backbones, which gave them additional speed and maneuverability in the water, where they hunted for fish and squids. Although the creatures were adapted for an aquatic predatory lifestyle, they could still drag themselves up on land, unlike their descendents the modern whales and dolphins. Additionally they still retained fur, and double-pulley heelbones (the latter of which convinced paleontologists that whales and cows are relatives who share an ancestor).

A Stegomastodon skeleton from the Smithsonian Museum of Natural History

A Stegomastodon skeleton from the Smithsonian Museum of Natural History

One of the most compelling extinct creatures from South America is not as well-known as it should be because it suffers from an incredibly confusing name.  The amazing Stegomastodon was a mighty proboscidean which lived on the great grassy lowlands east of the Andes until modern times, which is to say until about 9,500 years ago (because  paleontologists have a very different definition of modern than, say, historians or artists).  Proboscideans of course are the astonishing order of large mammals which include elephants and their many extinct relatives like mammoths, mastodons, deinotheriums,  moeritheriums…and stegomastodons.  The stegomastodons first evolved in North America during the Miocene (about 3 million years ago) and they lumbered rapidly down through South America after the Great American Interchange when the Isthmus of Panama formed between the two continents.  In North America, the stegomastodons died out because of competition from the true mastodons, which crossed over from Asia via Berengia, however deep in South America, they found ecosystems which suited them and they lasted for a long, long time.

An illustration of a stegomastodon (from geologiadelparaguay.com)

An illustration of a stegomastodon (from geologiadelparaguay.com)

Stegomastodons are neither stegodons nor mastodons, two famous and well known genera of proboscideans.  Confusingly stegomastodons are the last of the gomphotheres.  Gomphotheres wandered into Asia, became isolated and evolved into Stegodons, which, in turn, are the probable ancestors of today’s still-living elephants (assuming you are still reading this in an age when the Chinese and poachers have not wiped elephants from the globe).  If these relationships are confusing to you, you can use the proboscidean clade below (but remember that the stegomastodons are gomphotheres and they lasted much longer than is shown on the chart).

wpid-photo-aug-10-2012-1957Stegomastodons were grazers: they lived on the immense fields of grass which flourished east of the Andes in what is now Paraguay, Uruguay, Bolivia, and Argentina. The creatures were smaller than modern elephants growing only to 2,8 meters (9 feet) in height and obtaining a mass of 6,000 kilograms (13,000 pounds).  It is not known what wiped out the last stegomastodons, but they died quite recently, just after the Younger Dryas stadial was ending…only shortly after humankind made its way to the southern parts of South America.

Skull of stegomastodon waringii

Skull of Stegomastodon waringii

Bullockornis (with human-size silhouette for comparison)

Bullockornis (with human-size silhouette for comparison)

My sincere apologies for being such a truant blogger last week!  Not only did I fail to post any new articles since Tuesday, I unpardonably left you stuck with nothing but the flimsy Ms. Perry during that time. In order to apologize, allow me to take you on a trip to the island continent of Australia…15 million years ago during the Middle Miocene. During this time one of the largest birds ever lived across Australia: a giant fowl named Bullockornis.

Bullockornis

Bullockornis

Bullockornis was a 2.5 meter tall (8 foot 2 inch) gooselike bird.  The creature weighed in at approximately 500 kilograms (1100 pounds) and scientists believe it was actually related to the modern geese and ducks.   If you have ever met a modern goose, you will realize that a goose the size of a bear would be a formidable creature indeed.  Additionally Bullockornis possessed a razor sharp beak with immensely powerful jaw muscles.  It is hard not to imagine the giant bird nipping off a he-man’s arms like corn kernels or biting through bridge cables with this monstrous beak, but the truth is scientists don’t know what the bird used it for.  The monstrous goose could have been a hunting carnivore (like certain ducks are today) or an herbivore which grazed on heavy dense plants.  Perhaps, like contemporary geese, it was an omnivore which hunted, grazed, and opportunistically scavenged whatever it could get.

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Bullockornis was discovered in 1979 but it only became well known when some PR savvy writer christened it the “Demon Duck of Doom”  (which strike me as a silly 1930s Disney-style name, but I guess whatever gets people involved in paleontology is good).  The scientific name “Bullockornis”  means “bullock-bird” but, even though the bird was the size of an ox, it is actually named for Bullock Creek (a rich fossil location in the Northern Territory).  Bullockornis was not the only giant of the Miocene in Australia.  The Bullock Creek fossil beds also contained fossils of Giant horned tortoises, marsupial “lions” (i.e. thylacoleonids) and grazing Diprotodontids—giant wombats (although nothing so large as the mighty Diprotodon which evolved in the Pleistocene).

Fossil Bullockornis Skull

Fossil Bullockornis Skull

Wadi Al-Hitan, Egypt

In the desolate desert 150 kilometers southwest of Cairo there is a fearsome arid valley (wadi) of cliffs, carved buttes, and sandblasted erratic boulders.  The bleached landscape has an otherworldly emptiness as though it were located on a lifeless alien planet, though if you look closely, the desert is filled with austere furtive life like dorcas gazelles, tiny sand colored lizards, cobras, scorpions, and fennec foxes. The name of the place is even more otherworldly—“Wadi Al-Hitan” which is Arabic for “valley of the whales” and although the great smooth rocks buckling out of the sand might momentarily be taken for the backs of huge whales, the utter absence of the ocean (or of water of any kind) makes the name seem fanciful. The nearby Mount Garet Gohannam (which means mountain of hell because of the way it glows like flames at sunset) seems to be more aptly named.

Whale fossil at Wadi Al-Hitan

However the name of Wadi Al-Hitan is remarkably literal–for the valley contains the remains of hundreds of huge ancient cetaceans which died in the Eocene and were fossilized in the yellowish sandstone.  Forty million years ago the valley was a marine lagoon.  Although the remains of numerous sirenians, sawfish, sharks, rays, sea turtles, marine crocodiles, sea snakes, and even swamp dwelling moeritheriums have been discovered in the wadi, the valley takes its name from the most spectacular and numerous fossils which belong to four different species of primitive whales.  The most commonly discovered fossils belong to Dorudon, which was 3-5 meters long (9-15 feet) and fed on fish and mollusks, and to Basilosaurus, which was 15-22 meter (50-72 foot) and fed on everything else in the ocean.

Basilosaurus was first discovered in Louisiana in the early 19th century.  Its immense size and serpentine form initially convinced naturalists that it was a marine reptile and they misnamed the creature Basilosaurus (which means “king lizard”).  The mistake soon became obvious and Basilosaurus was classified among the Archaeoceti, a paraphyletic suborder of the cetaceans, however the giant kept its dinosaur name.  Different species of Basilosaurus flourished in oceans worldwide during the wet, tropical Eocene and, even though they were obviously very adept at ocean living (indeed rising to the top of the food chain) the creatures betray vestiges of terrestrial living which modern whales have entirely dispensed with. Not only do Basilosaurus fossils have teeth and jaws which retain reatures from their artiodactyl ancestors, they also have tiny vestigial back legs a mere half meter in length (which would scarely help a 22 meter animal get around).  Additionally Basilosaurus was different from modern whales in that it probably moved with eel-like horizontal thrashing of its long tail (modern whales move their flukes vertically).  Basilosaurus probably did not dive very deeply, but moved about near the surface of the oceans hunting for smaller marine animals.

Basilosaurus from “Life in the Ancient Seas Exhibit” at the Smithsonian Institution, National Museum of Natural History

Although Wadi Al-Hitan was discovered by Europeans in 1902-1903, some archaeologists and anthropologists have speculated that it was known long before that and have been irresistibly drawn towards comparing basilosaurus with the giant crocodiles and earth spanning serpent gods which populate ancient Egyptian cosmology.

Detail from painting (Life in the Ancient Seas Exhibit: Smithsonian Institution, National Museum of Natural History)

During the Mesozoic, the age of dinosaurs, mammals were widespread, but they kept a low profile so as to avoid the baleful attention of the great reptiles.   A fossil of one of these furtive early mammals was discovered last November (2011) in Argentina.  The creature was christened as Cronopio dentiacutus, and not only does the animal’s partial skull give us a window into mammalian form in the late Cretaceous it also provides a special treat for regular readers of Ferrebeekeeper, for like the Smilodon, the walrus, and the Odobenocetops, Cronopio has distinctly pronounced saber teeth (despite being a small scurrying squirrel-like creature).

A model of the Cronopio dentiacutus–which was only 10 to 15 cm (4 to 6 inches) long.

Cronopio dentiacutus was probably actually more shrew-like than squirrel-like and used its saber teeth for hunting insects.  Based on its large eye sockets, Cronopio most likely hunted its prey at night (when it could also more easily escape the attention of the dinosaurs and other larger predators.

Julio Cortázar, Argentine Surrealist author

Cronopio dentiacutus takes its species name from a Greek phrase meaning sharp teeth, but the origin of its genus name is rather more literary.  The Argentine surrealist writer Julio Cortázar wrote several books about abstracted categories of fictional entities and the Cronopio was the idealistic but disorganized type of being (as opposed to rigid, highly-organized “famas” and indolent, dull “esperanzas”).  It is unclear what creative/idealistic features of this insectivorous early mammal struck the fancy of the discovering paleontologist to provoke such a name, but it is nice to see scientists pay Argentine belles-lettres such an acknowledgement.

A few weeks ago Ferrebeekeeper featured a post about belemnites, extinct cephalopods from the Mesozoic which teemed in immense schools through the reptile-haunted oceans of that bygone era.  Yet belemnites were certainly not the only cephalopods which swam in the Mesozoic seas.  Numerous shelled cephalopods—the ammonites—were widespread in every sort of marine habitat.  Ammonites are personal favorites of mine so I am not going to write a comprehensive explanation/description of the subclass.  Instead I wish to provide you with an idea of how big ammonites could get by providing a few pictures of large ammonite fossils which have been discovered.   Imagine these monsters jetting through the water with huge tentacles and big intelligent eyes scanning for giant predatory reptiles and you will have a better idea of the Mesozoic Oceans!

This one is only .7 meters (two feet) in Diameter but it sure is pretty.

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

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