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McCartney publishes double skeleton fossil paper

Kevin McCartney, Professor of Geology at the University of Maine at Presque Isle, has recently published his latest paper in the international paleontology journal, Marine Micropaleontology. McCartney’s paper, which is titled Silicoflagellate double skeletons in the geologic record and serves as the cover story for the issue, results from research during the past six years on silicoflagellate double skeletons, and in particular from a Trustees Professorship in Japan last year.

Silicoflagellates are single-celled algae whose skeletons have an extensive fossil record and continue to live in modern oceans. The skeletons sometimes occur as pairs that are connected prior to reproductive division, much as two Amoeba split and separate. It is extremely rare, however, to find these double skeletons still attached together as fossils.

McCartney’s interest in these double skeletons began in 2009 with his first-ever personal observation of a fossil specimen. This example, which was from sediments of the Cretaceous age from northern Canada, was some 80 million years old, had the two skeletons connected differently than is observed of modern skeletons. This was, and remains, the oldest double skeleton ever found, but the odd configuration raises new questions about the group’s early history.

Since the original discovery, McCartney and his colleagues in Nebraska, Poland and Japan have sought additional examples and have published several papers on their findings. These include the first detailed study of modern silicoflagellate double skeletons, published last year in the same journal, Marine Micropaleontology. McCartney’s recent publication is thus a companion paper to the article on modern double skeletons that provides a summary of such skeletons throughout the geologic record.

In his paper, McCartney demonstrates that there were originally two groups of silicoflagellates that had distinctly different double skeleton configurations, and presents the hypothesis that there were originally two separate evolutionary lineages. One of these lineages became extinct about 40 million years ago and the other persists to the present. This hypothesis, if correct, will dramatically change the interpretation of early silicoflagellate evolution.

McCartney now has six papers that are published or in the review process that developed from his recent sabbatical to Japan and Poland. McCartney said the sabbatical is still paying dividends, both in terms of his continued research and his ability to present the scientific process to his university students. He is still actively working with colleagues in both countries on additional projects and hopes to return to these and other countries for further cooperative study.