Wooster’s Fossil of the Week: Reptile tracks from the Lower Permian of southern Nevada

November 6th, 2015

1 Komodo on slab side viewAlways lead with your most interesting image. The fossil here is the thin orange slab of siltstone underneath my magnificent Komodo Dragon model.
2 Footprints slabHere is the slab itself. On the far right and the far left you can see two fossil footprints from both sides of some ancient reptile. The plastic Komodo Dragon just happens to fit these prints in size and shape, but they certainly weren’t made by an actual Komodo Dragon. I found this rock in the Spring Mountains of southern Nevada while doing my doctoral dissertation fieldwork decades ago. It is from the Lower Permian of the massive Bird Spring Formation (which is almost a mile thick). The footprints had nothing to do with my work (I was concentrating on the Carboniferous part of the formation), so I kept this little slab as a memento at home.
3 Back right track copyThese tracks, a kind of trace fossil, belong to the ichnogenus Dromopus based on the slender nature of the elongated toes. Dromopus has been attributed to an araeoscelid reptile, which looked and apparently lived very much like a modern lizard.
4 Araeoscelis grandis by Smokeybjb WikipediaAraeoscelis is one of the earliest diapsid reptiles, a group that has two distinctive holes (temporal fenestrae) on the sides of its skull. Diapsids are the most common type of reptile today, including crocodiles, lizards, snakes and dinosaurs. This genus was small, growing only to about 50 cm, and apparently predatory on insects and other arthropods. (Image from Smokeybjb via Wikipedia.)

5 Komodo top view on slabAgain, my friendly Komodo Dragon is only a stand-in for the Permian tracemaker, but he does have a nice pose to fit the tracks of his ancestral cousin!


Haubold, H. and Lucas, S.G. 2003. Tetrapod footprints of the Lower Permian Choza Formation at Castle Peak, Texas. Paläontologische Zeitschrift 77: 247-261.

Hunt, A.P. and Lucas, S.G. 2006. Permian tetrapod ichnofacies. Geological Society, London, Special Publications 265: 137-156.

Hunt, A.P., Lucas, S.G., Lockley, M.G., Haubold, H. and Braddy, S. 1995. Tetrapod ichnofacies in Early Permian red beds of the American Southwest. New Mexico Museum of Natural History and Science Bulletin 6: 295-301.

Lucas, S.G. 2002. Global Permian tetrapod footprint biostratigraphy and biochronology. Permophiles 41: 30-34.

Wooster’s Fossils of the Week: Silicified productid brachiopods from the Permian of West Texas

July 18th, 2014

Productids ventral valves 052514The three beauties above are productid brachiopods from the Road Canyon Formation (Middle Permian, Roadian, approximately 270 million years old) in the Glass Mountains of southwestern Texas. They are part of a series we’ve done on the silicified fauna of a block of limestone we dissolved in the lab many years ago. The calcitic shells have been replaced with silica during the process of fossilization, so they can be extracted from the carbonate matrix with hydrochloric acid. This is a primary way we can see delicate parts of a fossil, like the long hollow spines above. Ordinarily these would have been lost under the usual processes of taphonomy.

The specimens are highly convex ventral valves, which are characteristic of the productid brachiopods. The long hollow spines helped distribute the weight of these brachiopods on soft and unstable substrata, like a sandy or muddy sediment. This is often called “the snowshoe effect”. Below is a diagram reconstructing productid brachiopods on a sandy substrate with their spines keeping them from sinking below the sediment-water interface.

productid diagramProductid Permian Texas 585Here is a closer view of the ventral valve exterior of one of these productid brachiopods. You can see how delicate the hollow spines are.

Productid interior ventral Permian Texas 585This is the interior of the same valve. Each spine has a hole connecting it to the inside of the shell. The mantle, which secretes the shell and has other physiological functions, extended out into each spine to build its length and possibly carry some sort of sensory abilities.

I have been unable to identify these brachiopods because of the bewilderingly large number of them described by Cooper and Grant in the 1960s and 1970s. Maybe one of our readers can give it a shot!


Brunton, C.H.C., Lazarev, S.S. and Grant, R.E. 1995. A review and new classification of the brachiopod order Productida. Palaeontology 38: 915-936.

Cooper, G.A., and Grant, R.E., 1964, New Permian stratigraphic units in Glass Mountains, West Texas. American Association of Petroleum Geologists Bulletin 48: 1581-1588.

Cooper, G.A., and Grant, R.E. 1966. Permian rock units in the Glass Mountains, West Texas, In: Contributions to stratigraphy, 1966: U.S. Geological Survey Bulletin 1244-E: E1-E9.

Cooper, G.A. and Grant, R.E. 1972. Permian brachiopods of West Texas, I. Smithsonian Contributions to Paleobiology 14: 1–228. [and five other volumes]

Shiino, Y. and Suzuki, Y. 2007. Articulatory and musculatory systems in a Permian concavo-convex brachiopod Waagenoconcha imperfecta Prendergast, 1935 (Productida, Brachiopoda). Paleontological research 11: 265-275.

Wooster’s Fossils of the Week: Silicified chonetid brachiopods from the Permian of West Texas

July 11th, 2014

Dyoros planiextensus Cooper and Grant 1975 585Above are four valves of the chonetid brachiopod Dyoros planiextensus Cooper and Grant, 1975. They are preserved by silicification and were recovered from a block of the Road Canyon Formation (Roadian Stage of the Guadalupian Series of the Permian System) from the Glass Mountains of southwestern Texas. It is from the same unit and location as the rhynchonellid brachiopod presented two weeks ago in this blog. (Please see that entry for additional links and explanations of the preservation.)

It took me awhile to work out the systematics of this species, so I must show you in exquisite detail —

Phylum Brachiopoda
Class Strophomenata Williams et al., 1996
Order Productida Sarytcheva and Sokolskaya, 1959
Suborder Chonetidina Muir-Wood, 1955
Superfamily Chonetoidea Bronn, 1862
Family Rugosochonetidae Muir-Wood, 1962
Genus Dyoros Stehli 1954
Species Dyoros planiextensus Cooper and Grant, 1975

Like music!

The chonetid brachiopods (at the suborder level) can be extremely common in Permo-Carboniferous units. I’ve seen hillsides in southeastern Ohio that seemed coated with them as they eroded from the shales beneath. They were well adapted to living on soft sediments with their flat, thin shells. In life they had a series of small hollow spines extended from the hinge line (the straight parts of the shell where the valves articulated; top in the photos above) to help anchor them as juveniles and possibly serve as extensions of their sensory systems.

Just a short entry this week. If all proceeded by plan, I’m somewhere deep in China right now!


Cooper, G.A. and Grant, R.E. 1975. Permian brachiopods of West Texas, III. Smithsonian Contributions to Paleobiology 19:795-1921.

Racheboeuf, P.R., Moore, T.E. and Blodgett, R.B. 2004. A new species of Dyoros (Brachiopoda; Chonetoidea) from Nevada (United States) and stratigraphic implications for the Pennsylvanian and Permian Antler Overlap assemblage. Geobios 37: 382-394.

Stehli, F.G. 1954. Lower Leonardian Brachiopoda of the Sierra Diablo. Bulletin of the American Museum of Natural History 105: 257-358.

Wooster’s Fossil of the Week: A silicified rhynchonellid brachiopod from the Permian of West Texas

June 22nd, 2014

Rhynchonellid crura Permian Texas 585Sometimes fossils can be more useful when broken than whole. Above is a much-abused rhynchonellid brachiopod from the Road Canyon Formation (Middle Permian, Roadian, about 270 million years old) found in the Glass Mountains of southwestern Texas. It is part of a set of silicified fossils we etched out of a block of limestone in the last century. The shell has been replaced with resistant silica, so it was easy to extract from the limestone matrix with a long bath in hydrochloric acid that dissolved the carbonate but left everything else. The fossils are like delicate little glass husks. We’ve featured them in this blog several times.

Update: Matt Clapham kindly corrected me in the comments, and it is worth repeating in the text: “It’s Stenoscisma. The large spoon-shaped projection is actually called a spondylium, formed from merged dental plates and it’s quite distinctive for the Stenoscismatidae. The crura are broken but still visible in your specimen; they are the little struts parallel to the narrowest part of the spondylium. There are five Stenoscisma species that appear common in the Road Canyon Formation and yours looks most similar to Stenoscisma triquetrum to me (weakly sulcate with ribs that are somewhat subtle but still extend near the beak).” I made a bonehead mistake labeling the spondylium incorreectly, hence the “c”. Here’s to the value of Twitter, blogging, and knowledgeable colleagues!
Rhynchonellid Permian Texas 585Here’s the dorsal side of the specimen for completion. The exterior is in poor shape.

I’d love to identify this specimen to at least the genus level [update: see above and the comments!], but there is not enough detail preserved, at least for my skill set. The Permian brachiopods of West Texas were famously studied by G. Arthur Cooper and Richard E. Grant in the 1960s and 1970s. The numbers of species are overwhelming in this ancient reef system, and almost all of them are preserved in this delicate way.


Cooper, G.A., and Grant, R.E., 1964, New Permian stratigraphic units in Glass Mountains, West Texas. American Association of Petroleum Geologists Bulletin 48: 1581-1588.

Cooper, G.A., and Grant, R.E. 1966. Permian rock units in the Glass Mountains, West Texas, In: Contributions to stratigraphy, 1966: U.S. Geological Survey Bulletin 1244-E: E1-E9.

Cooper, G.A. and Grant, R.E. 1972. Permian brachiopods of West Texas, I. Smithsonian Contributions to Paleobiology 14: 1–228. [and five other volumes]

Olszewski, T.D. and Erwin, D.H. 2009. Change and stability in Permian brachiopod communities from western Texas. Palaios 24: 27-40.

A surprising bit of Permian in central Sicily

June 7th, 2013

1. Sicilian Mountains 060713MARSALA, SICILY, ITALY–This morning the pre-conference field trip of the International Bryozoology Association headed into the mountains of central Sicily. The roads were steep and windy, as one would imagine, and the views of mountainsides, villages and fields spectacular. We were high enough to be in some small woods and scrub forests. Our goal was to see some mysterious blocks of Permian limestone seemingly out of place on an island dominated by Cenozoic sediments.
2. Palermo Geologists 060713We met a team of friendly geologists from the University of Palermo in the Sosio Valley near Palazzo Adriano. They were well prepared to tell a complicated story of tectonics in the classic geological manner: maps and charts held by students as a professor lectures. It was very effective, aided by the superb weather and amazing views.
3. Geological cross-section 060713In this geological cross-section, the Permian rocks are shown as blue. Already you see something odd with the same color of rock above and below the blue, showing that it is tectonically bounded. It is part of a melange (in the geological sense) of blocks of rock broken and thrust about during the tectonism of the Miocene. The Permian rock was recognized as such by its fossil content, which includes distinctive conodonts, fusulinids, brachiopods, bryozoans and corals. It sits surrounded by much younger Miocene sediments, demonstrating the complex tectonics leading to this unusual setting.
4. Permian melange fragment MioceneAbove is the Permian outcrop in the Sosio Valley. It stands out as very different from its surroundings by its lithology alone. I admire the geologists, though, who found diagnostic fossils within it — I saw just a very few highly recrystallized fusulinids and corals.
5. Museum Palazzo Adriano 060713For lunch we went to the city museum in Palazzo Adriano and had delicious sandwiches and cakes. There we saw some of the best fossils from the Permian outcrops on display.
6. Palazzo Adriano Church 060713This is one of the churches in Palazzo Adriano on the city square. It looks to be neglected on the exterior, but inside …
7. Palazzo Adriano Church Interior 060713… it is elaborate and well-maintained.

Wooster’s Fossil of the Week: An amphibian from the Permian of Germany

May 19th, 2013

Apateon_pedestris_Odernhelm_Germany_fixedThe above skeleton is of the salamander-like Apateon pedestris von Meyer 1840 from the Lower Permian of Odernhelm, Germany. There are just enough of these tiny little bones to show the ghostly outline of this freshwater amphibian. It is our only amphibian fossil at Wooster, and it is another gift from the George Chambers collection.

Apateon pedestris is in the Order Temnospondyli, a group thought to be ancestral to the modern salamanders. They would have lived much like their descendants today, spending most of their time in creeks and streams and wet leaf litter. It grew to a maximum length of about nine centimeters. Its head was wide and flat, presumably to aid in swimming. Some specimens are preserved with soft tissues intact showing that this species had external gills as an adult, a classic example of paedomorphosis (as my History of Life students will tell you).

homo diluvii testis-1The skull of our tiny specimen reminds me of a younger, larger and much more famous Miocene amphibian that went for a time under the surprising name Homo diluvii testis, meaning “evidence of a human at the time of the Noah’s Flood”. A drawing of the skeleton is shown above.

Johann Jacob Scheuchzer (1672-1733)

Johann Jakob Scheuchzer (above) described and interpreted Homo diluvii testis in Lithographia Helvetica (1726). He was convinced it represented a person (more likely a child) who was drowned in the Flood of Noah and then entombed in the sediments. The critical page from his book is shown below.

HdtJohann Jacob Scheuchzer (1672-1733) was a Swiss medical doctor and somewhat of a naturalist. He certainly had a gift for seeing a human pattern in these bones that is lost on us today — the skeleton is obviously not that of any kind of mammal. It is likely he was far too enthusiastic about finding what he considered solid proof of the Flood and a member of the wicked generation nearly killed off by it. Here is a bit of poetry he included in his fossil description:

Afflicted skeleton of old, doomed to damnation,
Soften, thou stone, the heart of this wicked generation!

homo diluvii testis

Much later the famous French scientist Georges Cuvier (1769-1832) had at Scheuchzer’s fossil (above). He showed that it was, of course, an amphibian. The name for it now is Andrias scheuchzeri — a perpetual honor for its sincere but deluded discoverer.


Fröbisch, N.B., Carroll, R.L. and Schoch, R.R. 2007. Limb ossification in the Paleozoic branchiosaurid Apateon (Temnospondyli) and the early evolution of preaxial dominance in tetrapod limb development. Evolution and Development 9: 69-75.

Fröbisch, N.B. and Schoch, R.R. 2009. The largest specimen of Apateon and the life history pathway of neoteny in the Paleozoic temnospondyl family Branchiosauridae. Fossil Record 12: 83-90.

Wooster’s Fossils of the Week: Silicified sclerobionts (Middle Permian of southwestern Texas)

October 21st, 2012

During my work at the National Museum of Natural History last week, I had my research desk amongst the many cabinets housing the famous Permian brachiopod collection made by the eminent paleontologist Richard E. Grant (1927–1995). Most of these specimens are from the Middle Permian of southwestern Texas, and they are preserved in a fantastic way. I peaked into some of these drawers and was just amazed at the beauty and delicacy of these fossils.

Many years ago I received a block of limestone from the Road Canyon Formation (Middle Permian, Roadian, about 270 million years old) found in the Glass Mountains of southwestern Texas. This rock was from an ancient reef system and so nearly completely filled with fossils. The fossils are replaced with very fine-grained quartz (“silicified”), yet the rock matrix around them is limestone (composed of calcium carbonate). The trick, then, is to dissolve away the limestone in hydrochloric acid and watch the delicate replaced fossils emerge. I did this with the Road Canyon Formation rock and recovered hundreds of extraordinary specimens. One set is shown above. Previous Fossils of the Week have included an aberrant brachiopod and a set of reef-forming brachiopods.
While at the Smithsonian, Kathy Hollis showed me a polished block of original Road Canyon Formation limestone (above) and then next to it the results after dissolving a similar block in acid (below). The complex mass of bryozoans, corals and brachiopods is preserved in exquisite detail.
Now, back to the Wooster specimens at the very top of this entry and just above. The platform is the wavy outer layer of a bivalve shell. Attached to it are encrusting organisms (sclerobionts). The long, gorgeous tube is a rugose coral. At its base is a ribbed athyrid brachiopod. Also in this vignette are bryozoans, additional corals and some really tiny productid brachiopods. Beautiful.


Cooper, G.A., and Grant, R.E., 1964, New Permian stratigraphic units in Glass Mountains, West Texas: American Association of Petroleum Geologists Bulletin 48: 1581-1588.

Cooper, G.A., and Grant, R.E. 1966. Permian rock units in the Glass Mountains, West Texas, In: Contributions to stratigraphy, 1966: U.S. Geological Survey Bulletin 1244-E: E1-E9.

Olszewski, T.D. and Erwin, D.H. 2009. Change and stability in Permian brachiopod communities from western Texas. Palaios 24: 27-40.


Wooster’s Fossil of the Week: A new microconchid genus and species (Permian of Texas)

December 4th, 2011

Two years ago I was invited to Texas by Tom Yancey (Texas A&M) to look at some curious wiggly tubular fossils in the Lower Permian (about 280 million years old). They form small reefs a meter or so across and have traditionally been referred to as serpulid worm tubes. We suspected otherwise. After field and lab work, and collaboration with our Estonian colleague Olev Vinn, we determined that they are a new genus and species of microconchid. Our paper describing this taxon has just appeared: Wilson, Vinn and Yancey (2011).

A tangled collection of Helicoconchus elongatus Wilson, Vinn and Yancey 2011.

Helicoconchus elongatus is, as you may suspect from the name, an elongate coiled tube. The walls are impunctate (meaning they have no pores) and have diaphragms (horizontal partitions) with little dimples in their centers. They have two kinds of budding: fission (shown in the top image) and lateral budding (shown below). They grew into thick intertwined disks in shallow marine waters where they lived with snails, clams, echinoids and foraminiferans.

A small lateral bud on the side of a microconchid tube.

An acetate peel showing a longitudinal cross-section of a microconchid tube. The thin diaphragm running vertically in this image shows an inflection for the "dimple".

Microconchids (Ordovician – Jurassic) are an evolutionarily interesting group because they appear to be related to bryozoans and brachiopods (much to everyone’s surprise). This is based on their shell structure and their manner of budding (Zatoń and Vinn, 2011). Helicoconchus elongatus will tell us much about the relationships of microconchids to other groups because of the detail we can see in its budding styles and its marvelous preservation.

Helicoconchus elongatus in the field.


Wilson, M.A., Vinn, O. & Yancey, T.E. 2011. A new microconchid tubeworm from the Artinskian (Lower Permian) of central Texas, USA. Acta Palaeontologica Polonica 56: 785-791.

Zatoń, M. & Vinn, O. 2011. Microconchids and the rise of modern encrusting communities. Lethaia 44:5-7.

Wooster’s Fossil of the Week: an aberrant brachiopod (Permian of Texas)

October 9th, 2011

Funny word to apply to a fossil: aberrant, meaning “deviating from the normal”. It’s an old-fashioned word rarely used these days, primarily because we have a hard time defining “normal”. It was the word used when I was introduced to the above brachiopod, though, so I employ it in honor of my old-timey professors.

On the left is the dorsal valve exterior and on the right the ventral valve interior of Leptodus americanus Girty 1908. (Both valves are broken.) This species is a member of the Family Lyttoniidae in the Order Productida, which some of my students may have just figured out. The large ventral valve relative to the reduced dorsal valve is the clue. The specimen was found in the Word Limestone (Wordian Stage, Guadalupian Series, Middle Permian System, about 265 million years old) in Hess Canyon, Texas. It is replaced by silica (“silicified”) and so was easily extracted from a block of limestone by dissolving away the calcium carbonate matrix.

These brachiopods, along with many other types, lived in extensive reefs in west Texas during the Permian. The ventral valve was cemented to other shells and extended out parallel to the substrate. The much smaller dorsal valve fit into the grooves, leaving much of the soft-part interior exposed. My professors said it was “like a leaf in a gravy boat” — and I had no idea what a “gravy boat” was then.

It is likely that Leptodus americanus had photosynthetic zooxanthellae embedded in its exposed mantle tissues. These are protists (most often dinoflagellates) that live inside the tissues of metazoans and provide them with nutrients and oxygen in return for carbon dioxide and a cozy place to live. Reef-forming corals are the best known animals to have such a mutualistic symbiotic relationship with zooxanthellae today. It would thus not be surprising to see a similar system with these reefal brachiopods.

Not so aberrant after all.


Girty, G.H. 1908. The Guadalupian fauna. United States Geological Survey Professional Paper 58:1-651.

Williams, A. 1953. The morphology and classification of the oldhaminid brachiopods. Washington Academy of Sciences Journal 9: 279-287.

Wooster’s Fossil of the Week: Reef-forming brachiopods (Middle Permian of southwestern Texas)

April 10th, 2011

In my early days of teaching paleontology I had an enthusiastic trading program with colleagues around the country. I would supply fine fossils from the Upper Ordovician of southern Ohio for what I considered exotic specimens from elsewhere. In one of the trades I received a block of limestone from the Road Canyon Formation found in the Glass Mountains of southwestern Texas. It was from the Roadian Stage of the Guadalupian Series of the Permian System, so about 270 million years old.

This limestone is famous for its silicified fossils. The original calcite shells of the fossils were replaced by silica (similar to the mineral quartz), yet the matrix of the limestone remained mostly calcite. This meant that my students and I could immerse the limestone block in hydrochloric acid and watch the calcite matrix dissolve and the silicified shells remain as an insoluble residue. What emerged from the acid were beautiful fossils where even the finest spines are preserved.

Cluster of Hercosestria cribrosa brachiopods with the conical ventral valve (VV) and lid-like dorsal valve (DV) labelled.

Our particular block was part of a reef complex in which the primary framework was made by conical brachiopods attached to each other by long spines. These brachiopods are unlike any that came before or since. Each shell consists of two valves: the ventral valve is an open cone and the dorsal valve attaches to it as a hinged lid. The spines come from the ventral valve and wrap around other shells to make a wave-resistant structure — a reef. These brachiopod reefs were unique to the Permian.

The species we have, Hercosestria cribrosa Cooper & Grant 1969, belongs to the Superfamily Richthofenioidea in the Order Productida, so they are often called richthofenids and productids. Hercosestria had its moment of paleontological fame in the mid-1970s. Two prominent paleontologists, Richard Cowen and Richard Grant, debated the role of models in assessing the functional morphology of extinct species.  Richthofenid brachiopods were used as an example: did they flap their dorsal valves to create a current (Cowen’s suggestion), or did they crack the valves open and pump the water in and out with their fleshy lophophores? Grant showed a specimen of Hercosestria cribrosa with another brachiopod living on its dorsal valve, convincingly demonstrating that the valves did not likely flap.

On the left is a figure from Grant (1975) showing Hercosestria cribrosa with a small brachiopod living on its dorsal valve; on the right is a side view of two H. cribrosa ventral valves with attaching spines.

To make it even more interesting, by the 1980s there was considerable support for the idea that richthofenid brachiopods like Hercosestria had algal symbionts in their tissues and thus were effectively photosynthetic!

Reconstruction of a Permian reef from the University of Michigan Exhibit Museum of Natural History.

To see the other Wooster’s Fossil of the Week posts, please click on this link or the appropriate tag to the right.

References —

Cooper, G.A. and Grant, R.E. 1969. New Permian brachiopods from west Texas. Smithsonian Contributions to Paleobiology 1: 1-20.

Cowen, R. 1975. ‘Flapping valves’ in brachiopods. Lethaia 8: 23-29.

Cowen, R. 1983, Algal symbiosis and its recognition in the fossil record: in Tevesz, M.J.S. and McCall, P.L., eds., Biotic Interactions in Recent and Fossil Benthic Communities: Plenum Press, New York, p. 431-478.

Grant, R.E. 1975. Methods and conclusions in functional analysis: a reply. Lethaia 8: 31–33.

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