It has been an absolute delight to work with the crinoid master Bill Ausich of The Ohio State University. He is not only one of the world’s top paleontologists, he’s a great guy. Bill taught me all I know about Paleozoic crinoids and their complex systematics. Last week our latest paper appeared on Silurian crinoids in Estonia, with the perceptive and observant Ursula Toom (Department of Geology, Tallin University of Technology) as our co-author. Here’s the abstract from the Journal of Paleontology—
“Three new Llandovery (early Silurian) crinoids from Estonia provide an improved understanding of the paleogeographic aspects of the crinoid diversification following the end-Ordovician extinctions. The new taxa are Euspirocrinus hintsae new species (Rhuddanian eucladid), Oepikicrinus perensae new genus new species (Aeronian camerate), and Rozhnovicrinus isakarae new genus new species (Aeronian eucladid). This brings the total of described Llandovery crinoids in Estonia to eight nominal species and a further three taxa in open nomenclature. The Rhuddanian radiation in Baltica mirrored that on Laurentia and Avalonia and was dominated by Ordovician clades that continued to diversify during the Silurian. Known Aeronian crinoids from Estonia continue these clades, whereas new clades diversified on Laurentia and Avalonia. However, by the Wenlock, a largely cosmopolitan fauna existed on Laurentia, Avalonia, and Baltica.”
Bill and I visited Estonia in the summer of 2018 to do this work, which took place primarily in Tartu and Tallin. We had a wonderful time with our Estonian friends. This particular project involved the description of new Silurian crinoids to help plot crinoid recovery and diversification after the end-Ordovician mass extinctions.
One of the new crinoids is shown above. It is Oepikicrinus perensae n. gen. n. sp., a new eucamerate from the Llandovery. The genus is named after Armin Öpik (1898–1983), an epic Estonian paleontologist. The species name recognizes Helle Perens, an expert Estonia geologist. The figure particulars: (1) lateral view of two paratypes, TUG 999-1-1 and 999-1-2; (2) lateral view of partially disarticulated paratype GIT 405-254-3; (3) lateral view of holotype GIT 405-254-1, with complete arms, also note long pinnules; (4) lateral view of compacted paratype GIT 405-254-2, with proximal arms. Scale bars = 1.0 mm (2); 2.5 mm (1, 3, 4).
The above plate shows the other two new crinoids. Rozhnovicrinus isakarae n. gen. n. sp., a new eucladid, is named after the prominent Russian paleontologist Sergei V. Rohznov and our Estonian friend and paleontological colleague Mare Isakar. Euspirocrinus hintsae n. sp., another new eucladid, is named for Linda Hints, an Estonian paleontologist who found the best specimen. The figure details: Rozhnovicrinus isakarae n. gen. n. sp.: (1) crown with damaged aboral cup, paratype TUG 1329-14-1; (2) two specimens, the larger with only an impression of the aboral cup is paratype GIT 405-252-1, and the smaller complete specimen is holotype GIT 405-252-2; (3) D-ray lateral view of aboral cup of paratype GIT 405-252-1; (4) enlargement of holotype GIT 405-252-2 and arms of paratype GIT 405-252-1 (see Fig. 5.2); (5, 6) paratype TUG 1329-14-4: (5) aboral cup and proximal arms; (6) enlargement of aboral cup; (7) Euspirocrinus hintsae n. sp., holotype GIT 405-256, note distal coiling of arms. Scale bars = 2.5 mm (1, 3–6); 5.0 mm (2, 7).
This all looks very esoteric when I write these highlights, but it was a challenging and fun project. This work is an example of systematics used to address paleoecological, evolutionary and biogeographic questions. It also represents the continuing work of a diverse, international team.
Ausich, W.I., Wilson, M.A., & Toom, U. 2020. Early Silurian recovery of Baltica crinoids following the end-Ordovician extinctions (Llandovery, Estonia). Journal of Paleontology, DOI: https://doi.org/10.1017/jpa.2019.89