These beautiful fossils were found in York State Park by Mae Kemsley (’16). It was a surprise gift I found on my doorstep! They are fossil barnacles completely covering the exterior of a valve of the pectenid bivalve Chesapecten middlesexensis (Mansfield, 1936) from the Upper Pliocene. An excellent example of an ancient sclerobiont community.
This is the reverse of the specimen, showing the interior of the host shell. Note the large single muscle scar typical of monomyarian pectenid bivalves.
Chesapecten is well known among paleontologists. The genus preserves a distinct evolutionary sequence, as seen in the above famous figure from Ward and Blackwelder (1975). This image has been reproduced in countless articles and textbooks.
Chesapecten was also the first fossil from North America to be illustrated in a scientific publication. The above image of what we now know as Chesapecten jeffersonius was illustrated in the third volume of Martin Lister’s Historiae Conchyliorum in 1687.
Martin Lister FRS (1639 – 1712) was a natural historian and physician born into a prominent family in Radcliffe, England. His father, Sir Martin Lister, was a member of the Long Parliament in the eventful politics of mid-17th century England. He was a nephew of James Temple, a regicide (or patriot, take your choice) and Sir Matthew Lister, physician to Charles I (victim of said regicide). These were just a few of his family connections to politics and science.
Martin Lister was graduated from St John’s College, Cambridge, in 1659, and a year later elected a fellow there. He served as a physician for many years in York, including three years as Queen Anne’s doctor. He became a Fellow of the Royal Society in 1671. He died in Epsom in 1712.
Martin Lister was an extraordinary naturalist, becoming the first conchologist (one who studies shells) and arachnologist (a spider expert). He was a prolific writer, so we know much about what he did, how he worked, and his motivations. He discovered ballooning spiders and invented the ubiquitous histogram. For us his most significant work was Historiae Conchyliorum (1685-1692), which had 1062 plates engraved by his daughters, Anna and Susanna. In keeping with his times, Lister noted the resemblances between fossil and modern shells, but believed the fossils were rocky replicas, not actual remnants of living organisms. He would no doubt be thrilled with our modern views of fossils and evolution.
Kelley, P.H. 1983. The role of within-species differentiation in macroevolution of Chesapeake Group bivalves. Paleobiology 9: 261-268.
Lister, M. 1687. Historiae Conchyliorum, volume III. Londini, aere incisi, sumptibus authoris.
Ward, L.W. and Blackwelder, B.W. 1975. Chesapecten, a new genus of Pectinidae (Mollusca, Bivalvia) from the Miocene and Pliocene of eastern North America: USGS Professional Paper 861. US Government Printing Office.