Archive for November, 2015

Wooster’s Fossil of the Week: A fragmentary rostroconch from the Middle Devonian of Ohio

November 27th, 2015

1 Hippocardia 1Not all of our featured fossils are particularly beautiful, or even entire, but they are interesting in some way. Above is the broken cross-section of a rostroconch mollusk known as Hippocardia Brown, 1843. It was found somewhere in Ohio by the late Keith Maneese and kindly donated to the department by his widow Cameron Maneese. From its preservation and the kind of rock making up the matrix inside, we can tell that it almost certainly came from the Columbus Limestone (Middle Devonian, Eifelian).

In the top image it is apparent that this fossil has bilateral symmetry, a heart-shaped cross-section, and a ribbed calcitic shell. This is the dorsal view.
2 Hippocardia 2Flipping the specimen upside-down, we now have a view of the ventral portion. Again we see the ribs and bilateral symmetry.
3 Hippocardia side viewThis side view shows that the ribs extend from the dorsal to the ventral sides and are angled to the axis of the shell. That’s about all we can tell. (And this is the best specimen of a rostroconch we have! Thank you again, Cameron.)
4 CzechVirtualRostroThis diagram of a complete rostroconch (from the Czech Virtual Museum). This is a side view of a species that does not have the dorsal-ventral ribbing. The shell is superficially like that of a bivalve (clam), but the valves are fused together and their is a distinctive tube (rostrum) extending to the posterior. Much study and debate about the rostroconchs has at least confirmed that these are a class of mollusks separate from the bivalves. They lived semi-infaunally with the rostrum extending into the seawater to channel a flow of water into the body chamber for filter-feeding, much like infaunal bivalves today that have siphons. Rostroconchs and cephalopods appear to be sister groups, and some rostroconchs may have evolved into the scaphopods. Plenty of arguments to go around, though, on the evolution and diversification of mollusks
5 Thomas 1843 p 976 Thomas pl 8 fig 10 1843Captain Thomas Brown (1785-1862) named the genus Hippocardia in 1843. He was a Scottish naturalist who studied many topics, including mollusks. Above are the sections of his book The Elements of Fossil Conchology that describe and illustrate Hippocardia (considering it a bivalve). Captain Brown was born in Perth and went to school in Edinburgh. He joined the militia at 20, becoming a captain at 26. When he was transferred to Manchester, England, Brown acquired an interest in nature. He bought a flax mill after leaving the military, but it burned down while still uninsured. He thus turned to nature writing for support. He was became a Fellow of the Royal Society of Edinburgh in 1818, and in 1840 he was appointed curator of the Manchester Museum. He retained this position for the rest of his life. He was later a Fellow of the Linnean Society and a member, in classic 19th Century fashion, of several other groups, including the Wernerian, Kirwanian and Phrenological Societies. (I love the addition of phrenology to his interests!) The marine gastropod Zebina browniana d’Orbigny, 1842, was named after him. An interesting character, this Captain Brown, but I’ve been unable to find a single portrait of him.

References:

Brown, T. 1843. The elements of fossil conchology according to the arrangement of Lamarck; with the newly established genera of other authors. Houlston & Stoneman, London; 133 pages.

Hoare, R.D. 1989. Taxonomy and paleoecology of Devonian rostroconch mollusks from Ohio. Journal of Paleontology 63: 838-846.

Pojeta, J., Jr., Runnegar, B. 1976. The paleontology of rostroconch mollusks and the early history of the phylum Mollusca. United States Geological Survey Professional Paper 968: 1-88.

Pojeta, J., Jr., Runnegar, B., Morris, N.J. and Newell, N.D. 1972. Rostroconchia: a new class of bivalved mollusks. Science 177: 264-267.

Runnegar, B., Goodhart, C.B. and Yochelson, E.L. 1978. Origin and evolution of the Class Rostroconchia [and discussion]. Philosophical Transactions of the Royal Society B: Biological Sciences 284(1001): 319-333.

Wagner, P.J. 1997. Patterns of morphologic diversification among the Rostroconchia. Paleobiology 23: 115-150.

Wooster’s Fossil of the Week: A tall brachiopod from the Devonian of western Russia

November 20th, 2015

1 Ladogia Nalivkin, 1941In the summer of 2009 I had a field adventure in Russia. It was an extraordinary time. I learned considerable amounts of Russian geology and paleontology, of course, and was immersed in the Russian geological culture. Along the way I collected the above unusual brachiopod. We are looking at its posterior (where the articulating hinge is), with the ventral valve below and dorsal valve above.
2 Ladogia Nalivkin, 1941This is the anterior view of the same specimen showing the junction between the valves (the commissure). The brachiopod is Ladogia Nalivkin, 1941, a rhynchonellid from the Upper Devonian (Frasnian) of the Central Devonian Field somewhere along the Syas River in the Leningrad Oblast of western Russia. We can immediately see that this brachiopod is very tall for its kind, with a strongly defined fold (the top part of the “anticline” in the dorsal valve) and sulcus (the lower folded surface in the  ventral valve). Note that the sulcus has several encrusting organisms, including eroded microconchids.
3 Ladogia Nalivkin, 1941The side view shows the dramatic upward sweep of the dorsal valve and the fine radiating ornamentation. The tall fold was effective in separating the incoming water for filter-feeding from the outflow of filtered water, essentially functioning like a chimney. Many brachiopods have such a fold and sulcus, but few have a set of such amplitude.
4 Nalivkin, Dmitrii VasilevichLadogia was described by Dmitrii Vasil’evich Nalivkin (1889-1982) in 1941. Nalivkin was a Soviet paleontologist and geologist born in 1889 in St. Petersburg. He graduated from the Institute of Mines in Petrograd (the name was changed from St. Petersburg) in 1915. In 1917 he joined the Geological Commission of Russia, staying a member through its many changes for over six decades. In 1920 he became a professor at the Institute of Mines after, we presume, the political situations from the Great War, the Bolshevik Revolution and the Russian Civil War calmed down. He is notable for giving the first lecture series on facies theory in the USSR in 1921. After World War II he was chairman of the Turkmen section of the Academy of Sciences. In 1954 he was made chairman of the Interdepartmental Stratigraphic Committee of the Academy of Sciences of the USSR. In 1954 he was appointed chairman of the Interdepartmental Stratigraphic Committee of the Academy of Sciences of the USSR. Nalivkin specialized in stratigraphy and paleontology of the Paleozoic, especially the Devonian and Carboniferous. He is best known for his geological maps of the USSR, for which he received the Lenin Prize in 1957. Here’s a man who saw a lot of history in his time.

References:

Nalivkin, D.V. 1941. Brachiopods of the Main Devonian field. Akademii Nauk SSSR Trudy 1: 139-226.

Sokiran, E.V. 2002. Frasnian-Famennian extinction and recovery of rhynchonellid brachiopods from the East European Platform. Acta Palaeontologica Polonica 47: 339-354.

Zhuravlev, A.V., Sokiran, E.V., Evdokimova, I.O., Dorofeeva, L.A., Rusetskaya, G.A. and Malkowski, K. 2006. Faunal and facies changes at the Early-Middle Frasnian boundary in the north-western East European Platform. Acta Palaeontologica Polonica 51: 747-758.

Wooster’s Fossil of the Week: A striated brachiopod from the Silurian of New York

November 13th, 2015

6 StriispiriferCalebsSometimes it is a Fossil of the Week simply because it is new to me. The brachiopods above are abundant in a thin layer of shells within the Lewiston Member of the Rochester Shale (Silurian, Wenlockian) in western New York State. They are well exposed in the magnificent Caleb’s Quarry a few colleagues and I visited this past summer.
2 Striispirifer niagarensis Bed 9 Mbr D

3 Striations Sheinwoodian 585I find this spiriferid brachiopod fascinating because of the fine striations it shows on its fold and sulcus (where the shell bends at its middle). I’ve never seen these before on a brachiopod. The species is Striispirifer niagarensis (Conrad, 1842). I know of no functional interpretation of these fine lines other than that they might have provided some micro-topography to dissuade encrusting organisms. (I observed, in fact, no encrusters on these shells, but that may be coincidence.) The Striispirifer shell pavement consists mostly of isolated valves, but there are occasionally clusters of articulated shells in living position. It appears likely this is a storm lag of shells that was later colonized by the same brachiopods composing it.
4 Conrad description niagaraensisWe met the species author Timothy Abbott Conrad (1803-1877) earlier in this blog. He described this brachiopod originally as Delthyris niagaraensis in 1842 (above). (The third “a” in the species name was dropped by James Hall in his species lists.) This name held for over a century until G. Arthur Cooper and Helen Muir-Wood discovered that the genus was also in use for another brachiopod named in 1828 by Johan Wilhelm Dalman. This made “Delthyris” a homonym, or a name for a taxon identical in spelling to another such name for a different taxon. We can’t have that, of course, since every genus name must be unique (at least among the animals). Cooper and Muir-Wood (1951) gave the later genus (the junior homonym) the new name Striispirifer. Paul Taylor and I recently had our own adventure with a homonym we inadvertently created.
5 Helen Muir Wood 1955 Jill DarrellHelen Muir-Wood (1896-1968) was one of the most prominent brachiopod experts of the 20th Century. The image above may be the first one of her online. (Thanks to Jill Darrell of the Natural History Museum, London, for providing it. Come to think of it, the earlier image of Rousseau Hayner Flower in this blog is likely the first picture of him on the web.) Muir-Wood was born in Hampstead, England, and educated at Bedford College, University of London (a college for women at the time). She joined the professional staff at the British Museum (Natural History) in 1922 and spent the next 43 years of her career there. She was a systemacist to the core, apparently intolerant of any work with with fossils outside of describing and classifying them. Although she did no fieldwork of her own, from her position at the museum she was able to study brachiopods from around the world. She pioneered the techniques of describing brachiopod internal structures and eventually had to her credit hundreds of new and redescribed taxa. She was awarded the Lyell Medal in 1958 for her achievements, and in 1965 received the Order of the British Empire. She was remarkably successful and her work is still heavily cited to this day.

References:

Ager, D. 1969. Helen Marguerite Muir-Wood. Proceedings of the Geologists’ Association 80: 122-124.

Brett, C.E. 1983. Sedimentology, facies and depositional environments of the Rochester Shale (Silurian; Wenlockian) in western New York and Ontario. Journal of Sedimentary Research 53: 947-971.

Conrad, T.A. 1842. Observations on the Silurian and Devonian Systems of the United States, with descriptions of new organic remains. Journal of the Academy of Natural Sciences of Philadelphia 8: 228–280.

Cooper, G.A. and Muir-Wood, H.M. 1951. Brachiopod homonyms. Journal of the Washington Academy of Sciences 41: 195-196.

Dalman, J.W. 1828. Uppställning och Beskrifning af de i sverige funne Terebratuliter. Kongl. Svenska Vetenskaps Academiens Handlingar, für 1827, 1828; Stockholm, tryckt hos P.A. Norstedt & söner, pp. 93, 99.

Williams, A. 1969. Helen Marguerite Muir-Wood. Proceedings of the Geological Society of London 1655: 123-125.

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!

References:

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.