North-western Pennsylvania Yields Up a Prehistoric Secret

Patience is one thing that geologists and palaeontologists need plenty of and when it comes to excavating and putting together one of the most ferocious marine predators known from the Palaeozoic fossil record, the patience of even the most dedicated scientist can be tried.

Dunkleosteus Fossil

In a secret location in Erie County (north-western Pennsylvania, United States), Scott McKenzie, assistant professor of geology at Mercyhurst University (Erie County), is returning to a site where the fossilised dermal armour plating of a giant placoderm is slowly eroding out of a stream bed gully.

The landowners are reluctant to permit a full excavation in the heavily wooded area so the assistant professor and his team have to wait for nature to do its job and slowly erode the fossilised pieces of dermal head shield from out of the sandy shale matrix.  For Scott, visiting the site at regular intervals to inspect the fossil bearing rock can be quite a depressing business.  Sometimes he finds no new fossil material.  With luck, he might be able to obtain enough material within a decade or so to make a presentable exhibit within the University’s Sincak Natural History Collection, where assistant professor McKenzie is the curator.

Primitive Jawed Fish

Placoderms were primitive jawed fish.  They are named placoderms “plated skins” after the wide, flat bony plates that covered the head and the anterior portions of the body.  They share a number of anatomical features with sharks and rays, for example, they had a body skeleton made of cartilage.  Most forms were relatively small, growing to less than sixty centimetres in length, but others were giants and the Erie County specimen represents a specimen of one of the most ferocious of all marine animals known to science – Dunkleosteus.

Dunkleosteus Specimen on Display

A Dunkleosteus cast on display. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

An Enormous Prehistoric Fish

Dunkleosteus was an enormous, prehistoric fish with an armoured head made up of several interlocking bony plates that covered up to thirty percent of this predator’s total length.  The placoderms (armoured fish); evolved in the Silurian geological period from ancestors that had no true teeth.  Instead this group of fish developed a pair of sharp bony plates that hung from the top jaw, whilst the edges of the lower jaw were also bony and extremely sharp.

The jaws could be closed together like a pair of self-sharpening shears and were powerful enough to cut a two metre long, primitive shark in half.  Most specimens of Dunkleosteus (D. terrelli) come from Ohio, so the discovery of a specimen in Pennsylvania might lead to the establishment of a brand new species of this type of armoured fishy carnivore.

An Illustration of the Fearsome Devonian Predator Dunkleosteus

Fearsome marine predator of the Late Devonian.

Picture credit: Everything Dinosaur

Late Devonian

The strata from which the dermal armour of this fossilised fish is being eroded from has been estimated to be around 365 million years old (Late Devonian).   During this period in Earth’s History much of the eastern part of the United States was underwater, this marine environment would have been a dangerous place to visit with the likes of Dunkleosteus in the water, an apex predator of the Late Devonian.

With the spring thaw Scott and his team are hopeful that more pieces of the body armour will have been revealed.  It is very unlikely that elements of the cartilaginous skeleton will have been preserved, but with the jaws and armoured head potentially being the size of a small car, the specimen once prepared and assembled will make a fine addition to the University’s natural history collection.

Scott commented that:

“Arguably, Dunkleosteus was the most terrifying creature during the Devonian, its huge jaws opened so fast they created a suction force that pulled prey into its mouth.  We’re restricted to surface collection, as the landowners do not want a significant excavation on their land and digging could actually damage the missing pieces.”

The Erie County Specimen

Although, the Erie County specimen is not as big as some of the fossils of Dunkleosteus found in Ohio, it is no tiddler.  The geologist calculates that the fossils represent an individual between five and eight metres in length and it probably weighed more than 1,000 kilogrammes.  He remains unsure whether this fossil material represents a specimen of D. terrelli or a new species.   This does represent the largest fish of its kind found in the Erie County area and an animal that could have given the legendary beast of Lake Erie, affectionately known as “Bessie” by locals a run for its money.

A Close up of the Huge Jaws of a Dunkleosteus

Fish with a powerful bite.

Picture credit: Everything Dinosaur

The picture above shows a close up a Dunkleosteus, with its dermal armour and huge jaws.  Safari Ltd have produced a superb model of a Dunkleosteus, it is part of the company’s Wild Safari Dinos and Prehistoric Life model collection.  Measuring a little under 19 centimetres in length the beautifully painted model is in approximately 1:50 scale.

To view the Safari Ltd range of prehistoric animal models: Safari Ltd. Prehistoric World Models.

The assistant professor and his team, kindly put on display at the University a number of pieces of the fossil specimen that they had already found, the bony plates although fragmented are an exciting discovery and the team are eager to see what the winter weather has managed to erode out of the matrix so that they can add to their collection.  At the moment the disarticulated and disassociated fossil pieces represent a 365-million-year-old jigsaw puzzle.

A true inspiration to students and other scientists, the dedication of Scott and his team as they try to piece together the county’s very own prehistoric monster is to be admired.  Fingers crossed for them, let’s hope that the wintry weather and the spring thaw provides them with yet more fossils for them to study as they continue their quest to prepare and mount their very own Dunkleosteus museum exhibit.

Fossil Tooth Provides Link Between Ceratopsians and Japan

Several Japanese news agencies have reported the discovery of a single, fossilised tooth of an ornithischian dinosaur in Japan.  The fossil tooth which comprises of a dental root joint is very distinctive. It has been identified as the tooth of a member of the Ceratopsia more specifically, it bares a close resemblance to a member of the Ceratopsidae (horned dinosaurs), a later and more advanced group of horned dinosaurs that include the likes of Triceratops, Styracosaurus and Chasmosaurus.

Did Japan Have its Own Version of Triceratops?

Evidence of Late Cretaceous ceratopsians from Japanese strata.

Picture credit: Everything Dinosaur

For models and replicas of articulated horned dinosaurs, take a look at the Beasts of the Mesozoic range of figures: Beasts of the Mesozoic Figures and Models.

Horned Dinosaurs

It is thought that the horned dinosaurs, part of the ornithischian group of the Dinosauria, evolved in Asia during the Cretaceous geological period.  For much of the Cretaceous, the land that we now know as Japan was underwater, that which was above sea level was not part of an island chain, but attached to the landmass that was to become Asia.  The numerous known genera of Japanese Cretaceous dinosaurs therefore have a strong affinity with Asian dinosaurs.  Evidence of hadrosaurs, sauropods and meat-eating theropod dinosaurs have been found in Japan, but this is only the second time fossils of a member of the Ceratopsia have been found and this new discovery represents a more advanced and later type of horned dinosaur.

To read about the discovery of a huge dinosaur thigh bone in Japan: Huge Sauropod Femur Discovered in Japan.

Japan’s Second Dinosaur Fossil Find

A spokesperson from the National Museum of Nature and Science in Tokyo commented that this was only Japan’s second fossil find that represents a member of the Ceratopsia.  The first fossil discovery, that of a dinosaur regarded as a member of the Neoceratopsia was found in the Hyogo Prefecture region of Japan (Honshu island).  Fossils of neoceratopsian dinosaurs have been found in China and Mongolia.

The fossil measures 1.21 centimetres in length and is 0.37 centimetres wide. It was found back in November 2011 during a geological survey of Campanian faunal strata on Shimo-koshiki Island (western tip of the main Japanese island chain).  The fossil is believed to be around 80 million years old (Late Cretaceous), a time when the giant horned dinosaurs roamed North America.  A detailed paper on this tooth discovery and its implications in terms of ceratopsian evolution and radiation will be presented at the June meeting of the Palaeontological Society of Japan to be held in Kumamoto Prefecture.

Late Cretaceous Ceratopsians

The jaws of Late Cretaceous ceratopsians, dinosaurs such as the famous Triceratops, Pachyrhinosaurus and Styracosaurus were lined with many hundreds of teeth. These teeth were strongly anchored to the jawbone by a “Y” shaped root structure.  The ceratopsians are the only dinosaurs to have this “Y” shaped dental root structure, in essence, to have two dental roots per tooth.  The actual crown of the tooth (the part of the tooth that sticks up from the jawline), was a square and blocky shape, ideal for crushing and grinding up tough vegetation.  It is likely that at the front of the mouth of this new Japanese ceratopsian there was a strong beak.  The beak was used to break off plant material before the strong and muscular tongue pushed the plant material further back into the jaws where the teeth could do their work, reducing the plant debris to pulp before it was swallowed.

An Illustration of a Tooth of a Typical Late Cretaceous Horned Dinosaur (Triceratops)

A typical tooth of a ceratopsian with its two distinct dental roots.

Picture credit: Everything Dinosaur

The tooth has been described as closely matching that of the Late Cretaceous North American member of the Chasmosaurinae ceratopsians – Triceratops (T. horridus).  Although, an adult Triceratops was estimated to have reached lengths in excess of nine metres, the Japanese tooth specimen indicates a much smaller animal, a cow-sized horned dinosaur between two to three metres in length.

Experts judged the length of the dinosaur’s body to be two to three meters or more, based on the size of the dental root.  The size estimate was based on the length of the tooth root and comparing this fossil specimen with other ceratopsian tooth fossils from better known Late Cretaceous genera.

An Insight on the Feeding Behaviour of Small Crocodyliforms – Watch out Hypsilophodonts You are on the Menu!

There have been a number of scientific papers published recently that provide information on the feeding habits of apex crocodyliform predators of the Late Cretaceous such as Deinosuchus.  Since modern day crocodiles and alligators attack and kill large mammalian vertebrates and are regarded as apex predators in their environments, it has long been thought that extinct crocodiles such as the twelve-metre-long Deinosuchus were also apex predators.  Instead of ambushing mammals when they came to a water source for a drink, (there are no large mammal species known from the Campanian/Maastrichtian fossil record), fearsome reptiles such as Deinosuchus are thought to have tackled dinosaurs.

Even a tyrannosaurid would have had to watch its step close to water with the possibility of being grabbed by a Deinosuchus, a type of crocodile getting on for twice the size of a Nile crocodile.

A Model of the Fearsome Late Cretaceous Predator Deinosuchus

The Carnegie Collectibles Deinosuchus crocodile model.

However, very little is known about interactions between predator and prey species when it comes to smaller types of Mesozoic crocodile and smaller types of potential prey.  Thanks to some new research by a team of American scientists evidence of a slightly smaller scale predator/prey relationship has been discovered.  It looks like small crocodyliform genera or indeed immature specimens of larger taxa may have fed on small types of dinosaur, or possible juveniles and babies of larger species.

Crocodyliforms Feeding on Small Dinosaurs

Writing in the Public Library of Science (Biology) publication Dr Clint Boyd (Department of Geology and Geological Engineering, South Dakota School of Mines and Technology, South Dakota, USA) and his colleagues have outlined research into a number of fragmentary dinosaur bones that show evidence of bite marks from crocodyliforms.  Moreover the jumbled and broken bones collected seem to represent a single ornithischian genus and an as yet, unknown genus to boot.  It looks like man-sized Cretaceous crocodiles fed on small dinosaurs and the remains of their dinner could well result in the erection of a new genus of hypsilophodontid dinosaur genus.

The Tiny and Fragmentary Dinosaur Bones – Ornithischian Dinosaur

Tiny dinosaur bones show evidence of crocodyliform bite marks.

Picture credit: South Dakota School of Mines and Technology

The fragmentary fossils were found in the Upper Cretaceous Kaiparowits Formation at four separate locations along the Grand Staircase Escalante-National Monument in southern Utah, an area famous for its dinosaur fossil finds.  The fossils are believed to date from the Campanian faunal stage of the Cretaceous and they are estimated to be around 75 million years old.

During this time in the Late Cretaceous, this region was a lowland plain, criss-crossed by many rivers.  The warm, humid climate created ideal conditions for lush plant growth and there was a rich and diverse dinosaur dominated ecosystem, with many types of crocodyliform also present.

Crocodyliforms Feeding

The broken dinosaur bones show bite marks and puncture wounds similar to those found on the bones of mammals that have been fed upon by extant American alligators.  The fossil are broken, many have been snapped off at the joints.  This could be characteristic of the damage to bones caused by the “crocodile roll” method of feeding, whereby extant crocodiles tear their victims to pieces by grabbing onto the corpse with their strong jaws and then rapidly rotating their bodies.

Studying the Fossil Material

The fossil material represents the bodies of several individual dinosaurs, all roughly 1.2 metres in length.  The fossils include elements of the limb bones and vertebrae, along with parts of the skull and the lower jaw.  As well as bite marks on the bones, the American research team discovered a broken Crocodyliform tooth embedded in a thigh bone (femur).

It can be speculated that baby ornithopod dinosaurs stayed together in groups when young to give themselves some protection, the nesting site may have been nearby and the two-metre-long crocodyliform predators lay in wait ready to ambush any unwary young herbivore that came too close.  The abundance and the close proximity of the fossil finds suggests that these relatively small crocodiles were actively targeting the hypsilophodonts, deliberately congregating close to areas where there were lots of dinosaur juveniles and actively selecting to feed upon these animals.

Although, only very small in size and hardly likely to feature in a major dinosaur exhibit in a museum, these fragments of bone are very significant as they are helping palaeontologists to piece together the complex food chain and diverse ecosystem in this Campanian faunal age environment.  It seems that life for a young hypsilophodontid in the Late Cretaceous was particularly hazardous, they would have had to look out for tyrannosaurs and dromaeosaurs as well as having to contend with predatory crocodiles.

A Drawing of What the Hypsilophodontid Dinosaur May Have Looked Like

Was this a meal for a Late Cretaceous crocodile?

Picture credit: Everything Dinosaur

The researchers have concluded that the chewed up bones are not the work of a much larger crocodile species.  If that had been the case, the bones would simply have been swallowed whole, leaving behind much fewer traces of the dinosaurs that it preyed upon.

Dr Boyd commented:

“It’s not often that you get events from the fossil record that are action-related. While you generally assume there was probably a lot more interaction going on, we didn’t have any of that preserved in the fossil record yet.  This is the first time that we have definitive evidence that you had this kind of partitioning, of your smaller crocodyliforms attacking the smaller herbivorous dinosaurs.”

Recently, Rebor have introduced a range of Deinosuchus figures.  To view this range of crocodyliforms (whilst stocks last): Rebor Models and Replicas.

Idaho State University Scientists Solve Spiral-Toothed Shark Puzzle

A team of researchers have got to the bottom of a fishy puzzle that had palaeontologists previously in a spin.  Fossils of an ancient cartilaginous fish known as Helicoprion show a whorl of spiral, saw-like teeth but up until now scientists were unsure where on this prehistoric fish the teeth whorl was located.  Was this strange toothed structure inside the jaw or outside, did it actually belong in the mouth at all, perhaps it formed part of a defensive structure located on the dorsal fin?  After all, the fossil record does contain some remarkable fossils of sharks, for example, Stethacanthus from the Late Devonian with a large projection known as the “ironing board” on its back.

Prehistoric Fish

Using their unrestricted access to the Helicoprion spiral-toothed fossils at the Idaho State Museum of  Natural History the research team were able to examine a number of beautifully preserved fossils.  This museum has the largest public collection of Helicoprion teeth fossils in the world and a number of these specimens have been collected from Early Permian strata exposed in Idaho.  The actual body shape of this large, prehistoric predator is open to speculation as since the skeleton of this animal was made of cartilage, very few fossils other than those of the strange teeth have been found.  It had been thought that Helicoprion was a nektonic and very active predator, patrolling the water column in a similar way to a lot of extant shark genera.

Previously, scientists had thought that this creature was a type of shark, however, this new research links this 270-million-year-old fish to another group of fish with cartilaginous skeletons.

A Scale Drawing of Heliocoprion

As Everything Dinosaur prepares for the arrival of Haylee the Helioprion model from PNSO a scale drawing of this Permian fish has been commissioned. Picture credit: Everything Dinosaur.

Picture credit Everything Dinosaur

Helicoprion

A large number of Helicoprion fossils were subjected to intense examination and analysis including computerised tomography – a process whereby high-powered X-rays bombard a fossil and provide non-destructive, three-dimensional images that reveal hidden aspects of anatomical structure.  One such fossil studied, measured over twenty-three centimetres in length and contained the remains of one hundred and seventeen individual, triangular teeth.  However, unlike most of the other known Helicoprion fossil material, this specimen had preserved impressions which showed the placement of parts of the cartilage skeleton.

Using the detailed computer images that the CT scans produced the team were able to deduce that the spiral teeth were located at the back of the jaw, the teeth did not project forwards from the lower part of the mouth, nor was this structure located on another part of the fish.  Dr Leif Tapanila of the department of Geosciences at Idaho State University and his colleagues have been able to clear up this mystery surrounding the whorl of teeth.

Tooth Whorl Analysis in Helicoprion

Helicoprion specimen IMNH 37899, preserving cartilages of the mandibular arch and tooth whorl. (a) Photograph and (b) surface scan of fossil. Picture credit: Tapanila et al in Biology Letters.

Picture credit: Tapanila et al

He stated:

“We were able to answer where the set of teeth fit in the animal.  They fit in the back of the mouth, right next to the back joint of the jaw.  We were able to refute that it might have been located at the front of the jaw.”

Studying the Wear Pattern

Analysis of the wear pattern on the teeth also provided the researchers with an insight into what this predator may have eaten as it swam in the Permian seas.  It is unlikely that these teeth were used to crush hard bodied creatures such as shellfish or marine snails.  It is more likely that Helicoprion tackled soft bodied members of the Phylum Mollusca such as cephalopods (squid and octopi).

A Scientific Paper

The paper, published in the prestigious academic journal “Biology Letters” provides further information on how the scientists think the jaws actually worked.  The jaw was able to produce a rolling-back and slicing action, ideally suited to tackling soft and slippery prey.  The research has also suggested that Helicoprion was not a type of shark, but that it is more likely closely related to the extant rat fish, making it a basal, but very specialised member of the Holocephalan group called the Euchondrocephali.

Dr Tapanila added:

“New CT scans of a unique specimen from Idaho show the spiral of teeth within the jaws of the animal, giving new information on what the animal looked like and how it ate.”

The teeth may be very shark-like with their triangular shape and serrated edges, but evidence from the CT scans indicates that Helicoprion should be classified as a Holocephalan.

The Idaho Fossil Specimen

The Idaho fossil specimen suggests an animal around 4.2 metres in length but other Helicoprion teeth fossils indicate fish that could have reached lengths in excess of 7 metres.  The work of the scientists will form the basis of a new Helicoprion exhibit that is to open shortly at the Idaho Museum of Natural History.

It seems that this creature was a specialised predator from the end of the Permian onwards the top predator niches in the world’s oceans were to be mainly occupied by sharks, before the evolution of the larger Teleost fish challenged the shark’s dominant position.

Helicoprion and Prehistoric Fish Models

Those clever people at Safari Ltd introduced a Toob (a tube containing models), called “Prehistoric Sharks” a couple of years ago now.  The models show different types of ancient cartilaginous fish including the likes of Stethacanthus and a model of Helicoprion.   This set of ten prehistoric fish has proved popular and it is fascinating to see how the interpretation of Helicoprion by the design team at Safari Ltd matches up against the latest scientific data.

The Helicoprion Model from the “Prehistoric Sharks” Toob

Model play set includes Helicoprion replica.

Picture credit: Everything Dinosaur

The snout may be somewhat elongated and the body perhaps a touch more streamlined, that of an active predator in the mid water column but the front jaw does resemble quite closely the latest scientific interpretation.

Helicoprion Up Close

A whorl of triangular teeth in this model’s lower jaw.

Picture credit: Everything Dinosaur

The morphology of this Early Permian predator may not be known but credit must be given to the design team at Safari Ltd for creating a replica that does have some similarities to the illustrations provided in the scientific paper.  It remains uncertain whether this shark was an active, fast swimming hunter or whether it lived close to the sea floor and had a more sedentary habit, but at least the mystery regarding its remarkable dentition (teeth) seems to have been solved.

PNSO Helicoprion Replica

PNSO Haylee the Helicoprion replica. The stunning emerald eye on the model is reminiscent of the eye of a Chimaera such as the deep water Rabbit Fish (Chimaera monstrosa) to which Helicorprion is distantly related.

PNSO have released a superb replica of this iconic prehistoric fish. To view the range of PNSO prehistoric animal models and figures available from Everything Dinosaur: PNSO Age of Dinosaurs Models.

Everything Dinosaur acknowledges the assistance of a press release from Idaho State University in the compilation of this article.

The scientific paper: “Jaws for a spiral-tooth whorl: CT images reveal novel adaptation and phylogeny in fossil Helicoprion” by Leif Tapanila, Jesse Pruitt, Alan Pradel, Cheryl D. Wilga, Jason B. Ramsay, Robert Schlader and Dominique A. Didier published in Biology Letters.