Wooster’s Fossils of the Week: Mosasaurid teeth from the Cretaceous of Morocco

June 30th, 2013

PrognathodonTeethKhouribgaCretaceousThese impressive teeth are from the mosasaurid Prognathodon and were found in the Upper Cretaceous phosphorites near Khouribga, Morocco. They are not actually a matching set — I just arranged them to look fearsome.

Prognathodon_lutigini_Dmitry_Bogdanov(Prognathodon lutigi from the Upper Cretaceous of Russia. Reconstruction by Dmitry Gogdanov via Wikipedia.)

Prognathodon (the name means “front-jaw tooth”) was a very large mosasaurid, with some specimens up to 12 meters in length. They were cosmopolitan in extent, being found throughout the world in Campanian to Maastrichtian deposits. They lived in deep waters as shown by some specimens with strengthening bony rings around their eye sockets. They were essentially sea-going lizards, and big ones at that.

Note that the teeth are stout and blunt. They were not adapted for tearing flesh but rather crushing hard-shelled prey they found on the seafloor. One skeleton was found with some stomach contents intact, including a sea turtle, a variety of fishes, and an ammonite. This is not the usual diet of other mosasaurid genera which were nektic (swimming) predators.
Louis_DolloPrognathodon was named in 1889 by the famous Belgian paleontologist Louis Antoine Marie Joseph Dollo (1857-1931). Paleontology and History of Life students will immediately recognize that name because of Dollo’s Law: “evolution is not reversible”. (Or its corollary: extinction is forever!) He started his career as an engineer, graduating at the top of his class in 1877 from the École Centrale de Lille. He worked as a mining engineer and, as luck would have it, quickly discovered an extraordinary mass burial of the dinosaur Iguanodon. Studying this genus and other fossil reptiles became his passion. In 1882 he became an assistant naturalist at the Royal Belgian Institute of Natural Sciences in Brussels. One of his many remarkable contributions was to begin to think of fossils as once living organisms in ecological networks. In this sense he essentially founded paleobiology. In 1912 he received the Murchison Medal from the Geological Society of London. Not too shabby for an engineer.


Buffetaut, E. and Bardet, N. 2012. The mosasaurid (Squamata) Prognathodon in the Maastrichtian (Late Cretaceous) of the Cotentin Peninsula (Normandy, northwestern France). Bulletin de la Societe Geologique de France 183: 111-115.

Schulp, A.S., Polcyn, M.J., Mateus, O.,  Jacobs, L.L., Morais, M.L. and Silva Tavares, T. 2006. New mosasaur material from the Maastrichtian of Angola, with notes on the phylogeny, distribution and palaeoecology of the genus Prognathodon. On Maastricht Mosasaurs 45: 57-67.

Wooster’s Fossil of the Week: A sawfish rostral tooth from the Upper Cretaceous of Morocco

June 16th, 2013

Onchopristis_numidus_052013_585More fossil fish teeth this week. This impressive, barbed tooth is from the ancient chondrichthyan sawfish Onchopristis numidus (Haug, 1905). It was found in the Tegana Formation (Cenomanian, Upper Cretaceous) near Kem Kem, Morocco (and is yet another contribution from our alumnus George Chambers).
Onchopristis_numidus_groupThese are all rostral teeth, meaning they are the sideways teeth on each side of the snout (rostrum) of the sawfish. They each have a barb for entangling prey. Like modern sawfish, O. numidus would have lived along the bottom and occasionally thrashed about, wounding smaller fish and crustaceans so that it could catch and eat them.

onchopristis_size_guideOnchopristis numidus was the largest sawfish known, making it a formidable predator.


Of course, seeing it against a human profile makes it more real!

Spinosaurus_OnchopristisDespite its size, O. pristis had a famous nemesis: the dinosaur Spinosaurus. Barbed teeth of the sawfish have been found embedded in the jaws of this beast. The above image is from the show Dinosaur Planet, as is this Youtube clip of the two struggling (with one clearly losing).

And yes, Spinosaurus is coming as a future Fossil of the Week!


Martill, D.M. and Ibrahim, N. 2012. Aberrant rostral teeth of the sawfish Onchopristis numidus from the Kem Kem beds (? early Late Cretaceous) of Morocco and a reappraisal of Onchopristis in New Zealand. Journal of African Earth Sciences 64: 71-76.

Slaughter, B.H. and Steiner, M. 1968. Notes on rostral teeth of ganopristine sawfishes, with special reference to Texas material. Journal of Paleontology 42: 233-239.

Slaughter, B.H. and Thurmond, J.T. 1974. A lower Cenomanian (Cretaceous) ichthyofauna from the Bahariya Formation of Egypt. Annals of the Geological Survey of Egypt 4: 25-40.

A visit to the Natural History Museum of Utah

May 29th, 2013

NHMU052913SALT LAKE CITY, UTAH–On the last full day of our Utah trip, we toured the Natural History Museum of Utah in Salt Lake City. It is in a spectacular place against the red rocks of the Wasatch Mountains and looking over the Salt Lake Valley. This museum has only been open since November 2011. Its exhibits are very up-to-date and modern.  (My test for recent accuracy is whether birds are acknowledged as dinosaurs and if Australopithecus sediba is in the human evolution section.) I’d like to just share some images from the museum and encourage anyone in Salt Lake City to visit it.

EoceneLake052913Dr. Judge will be impressed with the attention paid to exhibits on the Green River Formation (Eocene). This tableau is designed to show animals in the water (below) and on the beach (above). Note the stromatolites on the shoreline representing some of the features she and her students have worked on in the Green River Formation.

585_Deinosuchus_hatcheri_052913Utah is extremely rich in Mesozoic vertebrate fossils. Here is an impressive skeleton of Deinosuchus hatcheri from the Cretaceous.

CeratopsianWall052913The dinosaur exhibit is world-class. Here is a wall of ceratopsian dinosaur skulls showing evolutionary relationships.

DinoPelvis1_052913My History of Life students are well trained in sorting out major dinosaur groups by their pelvic bones. They could tell you, for example, if this is an ornithischian or a saurischian dinosaur.

DinoPelvis2_052913And this set is of the other group. Can you see the differences?

dinohead052913It appears this dinosaur had barnacles for eyes!

PaleontologistsBehindGlass052913Here is the classic paleontologists-behind-glass exhibit of a working laboratory. (I wonder why they never put working petrologists on display?)

NHMUview052913The architects knew exactly what they were doing when it came to designing the building to take full advantage of the setting. The Salt Lake Valley is fully visible from every floor.

What a great place to end our little Utah excursion this year. The real Team Utah of Wooster Geology will be back in the state next month.

Wooster’s Fossil of the Week: Sea urchin bites from the Upper Cretaceous of southern Israel

February 10th, 2013

GnathichnusCenomanian020413_585What you see above is a bit of oyster shell with some curious small gouges in it. The oyster is Ilymatogyra (Afrogyra) africana (Lamarck, 1801) from the En Yorqe’am Formation (Cenomanian) exposed in Hamakhtesh Hagadol, southern Israel. The deep scratches are the trace fossil Gnathichnus pentax Bromley, 1975. As you can just make out in the lower center of the image, the grooves are overlapping series of five-pointed stars. That’s what makes this trace so cool — the stars were made by the unique feeding apparatus of a regular echinoid (sea urchin).
Strongylocentrotus_purpuratus_020313_585This is the business end of the modern sea urchin Strongylocentrotus purpuratus (a preserved specimen in Wooster’s collection). You see here in the center the peristome, which is a circle of plates surrounding the mouth, with the sharp five-sided teeth protruding from the echinoid’s Aristotle’s Lantern. These animals slowly graze across hard substrates, using their teeth to scrape the surfaces for algae, fungi and adherent organisms like diatoms. The biting actions of the Aristotle’s Lantern produce the star-shaped incisions we know as the trace fossil Gnathichnus pentax.

I briefly sampled and studied an exposure of the fossiliferous En Yorqe’am Formation in 2003 during my first visit to Israel. The oyster shells in this unit provide one of the few examples of hard substrate communities in the tropics of the Late Cretaceous. The encrusters include ostreid and spondylid bivalves, the cyclostome bryozoan Stomatopora, and the agglutinating foraminiferan Acruliammina. Borings include those of barnacles (Rogerella elliptica) and sponges (Entobia aff. E. megastoma). There is also a sea urchin present (Heterodiadema lybicum) that was almost certainly the maker of the Gnathichnus pentax traces.


Bromley, R.G. 1975. Comparative analysis of fossil and recent echinoid bioerosion. Palaeontology 18: 725-739.

Wilson, M.A. 2003. Paleoecology of a tropical Late Cretaceous (Cenomanian) skeletozoan community in the Negev Desert of southern Israel. Geological Society of America Abstracts with Programs 35(6): 420.

Wooster’s Fossils of the Week: Shark teeth! (Upper Cretaceous of Israel)

December 2nd, 2012

This week’s set of exquisite fossils is presented in honor of Andrew Retzler (’11) who has just had his Senior Independent Study thesis at Wooster published in the journal Cretaceous Research: “Chondrichthyans from the Menuha Formation (Late Cretaceous: Santonian–Early Campanian) of the Makhtesh Ramon region, southern Israel“. The above beauties are a mix of Scapanorhynchus teeth found in the southwestern portion of Makhtesh Ramon during Andrew’s study in the summer of 2010. We were ably assisted by Micah Risacher and Yoav Avni with these collections.

Andrew identified at least eight shark species and two other fish species in the Menuha Formation around Makhtesh Ramon. Most of the teeth are from a soft yellowish chalk with relatively few other fossils (mostly oysters, echinoids, foraminiferans and traces). They show that the Menuha was deposited in a shallow, open-shelf environment on the flanks of the developing Ramon anticline. So, they not only provide new information about Cretaceous sharks in the Middle East, they help sort out a complex stratigraphic-structural problem.

Well done, Andrew! (Andrew is currently a graduate student at Idaho State University. He is working on the Late Devonian Alamo Impact Event in Nevada with Dr. Leif Tapanila.)

Tooth of the shark Cretalamna appendiculata. Composite photo by Andrew Retzler.

Scapanorhynchus rapax, another shark species. Composite photo by Andrew Retzler.

An elegant Scapanorhynchus texana tooth.

Looking south at one of the productive exposures of the Menuha Formation (shown as the red dot) at Makhtesh Ramon. This is one of those amazing Google Earth images.

Wooster’s Fossil of the Week: an encrusted plesiosaur vertebra (Jurassic of England)

July 29th, 2012

The weathered bone pictured above sits on my desk as a treasured memento. It is the centrum of a plesiosaur vertebra. I found it in the Faringdon Sponge Gravels (Lower Cretaceous) of Oxfordshire, England, during my first research leave (1985). I was working on a project involving encrusters, borers and nestlers (now called sclerobionts) on and in cobbles in this marine gravel (Wilson, 1986). This bone rolled out of the gravels at my feet during a particularly rainy field day.

But why do I say in the title that this vertebral fragment is Jurassic if it is found in a Cretaceous deposit? Because it is what paleontologists call a remanié fossil, a fossil reworked from an earlier deposit into a later one. During the Early Cretaceous, tidal currents worked on an exposure of Jurassic claystones in what will become southern England, eroding bones and other Jurassic debris and transporting them into a gravel-filled channel.

This gravel consisted of bones, shells, quartzite pebbles and claystone cobbles. It was tossed around under marine conditions, with many of their surfaces encrusted and bored by invertebrates. If you look closely at the end-on view above, you can see some lighter-colored patches that represent little calcareous sponges. When I collected this bone these sponges were the important parts. Now I’m impressed more by the fact that it is a bit of plesiosaur.

Plesiosaurs (the name means “near-lizard”) were magnificent marine reptiles of the Jurassic and Cretaceous. They were extraordinary predators on a variety of animals, and despite their bulk were highly maneuverable because of their four large paddle-like appendages. My little bone is too weathered to place in the complex plesiosaur skeleton, other than to say it is probably from the back rather than the neck or tail. Rather than me wax poetic on the Plesiosauria, you might want to visit Plesiosaur.com.

The first plesiosaur (Plesiosaurus dolichodeirus) was found by one of the most famous paleontologists of the 19th Century: Mary Anning (1799-1847). Anning was a spectacularly successful fossil collector along the “Jurassic Coast” of southern England. She had a tough life, selling fossils to support her family. She discovered many Jurassic fossils, from ammonites to ichthyosaurs and plesiosaurs. The paleontological establishment at the time often bought fossils from her, but they didn’t always give her credit for her work.

Little known fact: Mary Anning was the inspiration for the classic tongue-twister, “She sells seashells on the seashore. The shells she sells are seashells, I’m sure. So if she sells seashells on the seashore, then I’m sure she sells seashore shells.” I’m sure she’s proud!

To Mary Anning and her magnificent plesiosaur!


Conybeare, W.D. 1824. On the discovery of an almost perfect skeleton of the Plesiosaurus. Transactions of the Geological Society of London, Second series; 1 p. 381-389.

Goodhue, T.W. 2002. Curious Bones: Mary Anning and the Birth of Paleontology (Great Scientists). Morgan Reynolds.

Wilson, M.A. 1986. Coelobites and spatial refuges in a Lower Cretaceous cobble-dwelling hardground fauna. Palaeontology 29: 691-703.

Wooster’s Fossil of the Week: a long and skinny bryozoan (Upper Cretaceous of Wyoming and South Dakota, USA)

June 17th, 2012

Please say hello to Pierrella larsoni Wilson & Taylor 2012 — a new genus and species of ctenostome bryozoan from the Upper Cretaceous (Campanian-Maastrichtian) Pierre Shale of Wyoming and South Dakota. I imagine it as a graceful little thing spreading delicately through the dark interiors of baculitid ammonite conchs on a muddy Cretaceous seafloor. Above is a fossil of Baculites formed when sediment filled the shell and lithified. The shell itself dissolved away, leaving the internal mold  of rock (or steinkern) as a kind of cast of the interior. (But don’t ever call it a “cast”!) Pierrella larsoni encrusted the inside surface of Baculites and is thus preserved as a series of connected teardrops on the outside of the internal mold. The specimen is from Heart Tail Ranch, South Dakota, and the scale bar is 10 mm. (Baculites was described in an earlier Fossil of the Week post.)

My friend Paul Taylor (The Natural History Museum, London) and I had a wonderful field trip to South Dakota and Wyoming in June 2008. We were accompanied by my ace student John Sime (who is a spectacular field paleontologist) and greatly helped by the distinguished paleontologist and ammonite expert Neal Larson (Black Hills Institute of Geological Research), Bill Wahl (Wyoming Dinosaur Center), and Mike Ross, an avid amateur paleontologist in Casper, Wyoming. We also had assistance from Walter Stein (PaleoAdventures) and the enthusiastic and knowledgeable amateur paleontologist Jamie Brezina. You can see some images from our trip here.
The primary purpose of our expedition was to find and study Late Cretaceous bryozoans. Our paper describing this work has now appeared in a special volume on bryozoan research. The specimen above on the left is from Red Bird, Wyoming, and the one on the right is from the Heart Tail Ranch in South Dakota. The scale bars are 10 and 5 mm respectively.
Above is a typical example of the Pierre Shale exposures we worked with on this trip. This particular shot is from the Chance Davis Ranch in South Dakota, but they all looked pretty much the same. We crouched down and scanned miles of “outcrop” like this, picking fossils up from the ground.

Finding ctenostome bryozoans preserved like this is unusual. They did not (and do not today) have calcareous skeletons. These Pierre specimens were somehow preserved as the internal molds formed, most likely through some process of early cementation of the mud. I described this fossil fauna and its preservation in an earlier post from a GSA meeting.

Pierrella is named after the Pierre Shale; larsoni after our colleague Neal Larson. It is nice to have locked into the name direct reminders of that delightful summer under those big Western skies.


Wilson, M.A. and Taylor, P.D. 2012. Palaeoecology, preservation and taxonomy of encrusting ctenostome bryozoans inhabiting ammonite body chambers in the Late Cretaceous Pierre Shale of Wyoming and South Dakota, USA. In: Ernst, A., Schäfer, P. and Scholz, J. (eds.) Bryozoan Studies 2010; Lecture Notes in Earth Sciences 143: 399-412.

Wooster’s Fossil of the Week: a very large clam (Upper Cretaceous of South Dakota, USA)

June 3rd, 2012

Our version above of the bivalve Inoceramus is actually rather small compared to how big it can get. The record holder is a specimen 187 centimeters in diameter (over six feet) in the Geological Museum of Copenhagen. This Wooster Inoceramus is from the Pierre Shale of South Dakota, a unit my colleague Paul Taylor and student John Sime once explored in some detail.

Inoceramus means “strong pot”, which I assume must refer to its unusually thick shell with calcite prisms oriented perpendicular to the surface. They also had concentric “wrinkles” that make them easily identifiable even in small fragments. In fact, we can even recognize the isolated prisms of inoceramids in thin-sections of sedimentary rocks. This genus was widespread during the Late Cretaceous, being found from British Columbia to Germany. The had very large gill systems that enabled them to live in poorly-oxygenated waters. It makes sense that they are so common in the dark, carbon-rich sediments of the Pierre Shale.
Inoceramus was named by the dapper James Sowerby (above) in 1814, so it is a genus we have known for a very long time. Sowerby (1757-1822) was an Englishman skilled in natural history as well as scientific illustration. He named the first species of the genus as Inoceramus cuvieri to honor the French scientist Georges Cuvier. His illustration of I. cuvieri is below.
Inoceramus was one of the first invertebrate fossils to be the subject of an evolutionary study in a modern way. Woods (1912) studied various species of Inoceramus in the Cretaceous, noting that it apparently underwent rapid intervals of change. My former student Colin Ozanne and his advisor (and my friend) Peter Harries studied Inoceramus and its relatives in the Western Interior Seaway. Their study, published in 2002, showed that inoceramids were greatly stressed by parasites and predators before their final extinction in the Maastrichtian.


Ozanne, C.R and Harries, P.J. 2002. Role of predation and parasitism in the extinction of the inoceramid bivalves: an evaluation. Lethaia 35: 1–19.

Sowerby, J. 1822. On a fossil shell of a fibrous structure, the fragments of which occur abundantly in the chalk strata and in the flints accompanying it. Transactions of the Linnean Society of London XIII: 453-458. Plate XXV.

Woods, H. 1912. The evolution of Inoceramus in the Cretaceous Period. Quarterly Journal of the Geological Society 68: 1-20.

Wooster’s Fossils of the Week: Intricate networks of tiny holes (clionaid sponge borings)

May 13th, 2012

The most effective agents of marine bioerosion today are among the simplest of animals: clionaid sponges. The traces they make in carbonate substrates are spherical chambers connected by short tunnels, as shown above in a modern example excavated in an oyster shell. The ichnogenus thus created is known as Entobia Bronn, 1838. I’ve become quite familiar with Entobia throughout its range from the Jurassic through the Recent (with an interesting early appearance in the Devonian; see Tapanila, 2006).
The holes in this Cretaceous oyster are the sponge boring Entobia; the cyclostome bryozoan is Voigtopora. This specimen is from the Coon Creek Beds of the Ripley Formation (Upper Cretaceous) near Blue Springs, Mississippi. (This specimen was collected during a 2010 Wooster/Natural History Museum expedition to the Cretaceous and Paleogene of the Deep South.)
This is a modern clam shell showing Entobia and several other hard substrate dwelling organisms (sclerobionts).
Entobia was named and first described by Heinrich Georg Bronn (1800-1862), a German geologist and paleontologist. He had a doctoral degree from the University of Heidelberg, where he then taught as a professor of natural history until his death. He was a visionary scientist who had some interesting pre-Darwinian ideas about life’s history.


Bromley, R.G. 1970. Borings as trace fossils and Entobia cretacea Portlock, as an example. Geological Journal, Special Issue 3: 49–90.

Bronn, H.G. 1834-1838. Letkaea Geognostica (2 vols., Stuttgart).

Tapanila, L. 2006. Devonian Entobia borings from Nevada, with a revision of Topsentopsis. Journal of Paleontology 80: 760–767.

Taylor, P.D. and Wilson, M.A. 2003. Palaeoecology and evolution of marine hard substrate communities. Earth-Science Reviews 62: 1-103.

Wilson, M.A. 2007. Macroborings and the evolution of bioerosion, p. 356-367. In: Miller, W. III (ed.), Trace Fossils: Concepts, Problems, Prospects. Elsevier, Amsterdam, 611 pages.

Wooster’s Fossils of the Week: Three cobble-dwelling oysters from the Upper Cretaceous of southern Israel

March 25th, 2012

These fossils of the week, three well-worn cemented oysters, are highlighted to celebrate the final acceptance this past week of a manuscript that describes their geological setting and significance: Wilson et al., 2012 (see reference below). They are attached to a cobble found at the base of the Menuha Formation (Santonian) near Makhtesh Ramon in southern Israel. These oysters represent the many sclerobionts that inhabited these cobbles. Here is the abstract of the paper:

Reworked concretions have been significant substrates for boring and encrusting organisms through the Phanerozoic. They provide large, relatively stable calcareous surfaces in systems where sedimentation is minimal. Diverse sclerobiont communities have inhabited reworked concretions since the Ordovician, so they have been important contributors to our understanding of the evolution of these ecological systems. Here we describe reworked concretions from southern Israel where they are critical for interpreting the stratigraphy and paleoenvironment of an Upper Cretaceous sedimentary sequence. These cobble-sized concretions (averaging roughly 1000 cubic centimeters) are found at the base of the Menuha Formation (Santonian to lower Campanian, Mount Scopus Group) unconformably above the top of the Zihor Formation (Turonian-Coniacian, Judea Group) exposed in the Ramon region of the Negev Highlands. The concretions are almost entirely composed of micritic limestone, and many are exhumed cemented burrow-fills apparently from 10-20 meters of upper Zihor Formation strata removed by erosion. There are also a few cobbles of dolomitic limestone and rare vertebrate bone. The cobbles are moderately to heavily bored by bivalves (producing Gastrochaenolites) and worms (forming Trypanites), and a few have cemented oysters. They are densely arrayed in a single layer, often touching each other or only a few centimeters apart. The sclerobionts associated with the cobbles, along with their hydrodynamic arrangement, strongly suggest that these cobbles accumulated in very shallow water above normal wave base. Most of them (77%) are encrusted on their top surfaces only, indicating that they were bored in place and not later delivered to a deeper environment by submarine currents. The rest of the Menuha Formation above is a chalk with relatively few macrofossils (primarily shark teeth and oysters) and a few trace fossils (Planolites and Thalassinoides are the most common). These reworked cobbles show that the initial deposits of the Menuha Formation accumulated in very shallow water. This has important implications for the development of the Syrian Arc structures in this region, especially the Ramon Monocline.

Two cobbles in their natural setting: embedded in the chalks at the base of the Menuha Formation.

The beautiful setting south of Makhtesh Ramon. The cliff is an exposure of the resistant Zihor Formation; above it are the white slopes of the far less resistant chalky Menuha Formation. The cobbles are found at the base of the Menuha.

A figure from the manuscript itself showing a cross-section of a cobble. The “T” indicates a Trypanites boring; the “G” shows a Gastrochaenolites boring.

Thank you again to Wooster alumni Micah Risacher and Andrew Retzler and current student Will Cary for helping us collect these specimens!


Wilson, M.A., Zaton, M. and Avni, Y. 2012. Origin, paleoecology and stratigraphic significance of bored and encrusted concretions from the Upper Cretaceous (Santonian) of southern Israel. Palaeobiodiversity and Palaeoenvironments (in press).

« Prev - Next »