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Posted on: October 28, 2021

LOCAL FOSSILS RETELL PREHISTORIC SHARK BITE Story of extinct shark scavenging!

21-25 Figure 2

 

FOR IMMEDIATE RELEASE 

Date: October 28, 2021
Contact: Bonnie Farmer, Communications & Marketing Coordinator
410-326-2042, ext. 8067 Email: Bonnie.Farmer@calvertcountymd.gov

LOCAL FOSSILS RETELL PREHISTORIC SHARK BITE
Story of extinct shark scavenging!

SOLOMONS, MD – October 28, 2021 – Locally found fossils tell an incredible story of interaction between a prehistoric shark and whale. In a recently published paper in the French paleontological journal, Carnets de Geologie, Calvert Marine Museum (CMM) paleontologists describe a 12-15 million- year-old Miocene baleen whale radius (one of the flipper bones) that was bitten repeatedly by a prehistoric shark (Fig. 1). 

The shark bites and head-thrashings were so forceful that both the upper and lower teeth in the jaws of the shark cut multiple gouges into the whale bone. At least three successive bite-shake traces, made by multiple teeth, mark both the upper and lower sides of the whale radius. These bite-shake traces consist of shallow, thin arching gouges that likely indicate scavenging rather than active predation (Fig. 2). The most likely way the three sets of shark bite-shake traces would have been made were by repeated biting as the shark re-positioned the whale flipper in its mouth to remove flesh. (Fig. 2).

 “This bone is very unusual because it preserves so much evidence of head-thrashing behavior of an extinct shark feeding on an extinct whale” said CMM Curator of Paleontology, Dr. Stephen Godfrey. 

The well-preserved bone was found along Calvert Cliffs, one of the most fossiliferous regions on the east coast of the continental United States, by local fossil hound Douggie Douglass. In addition to the innumerable body fossils, the Calvert Cliffs preserve trace fossils, which reveal evidence of animal behavior, including burrows made by invertebrates, coprolites (fossilized poop), and fossilized bones with shark bite traces.

We invite visitors to view this and other fossils in our Mezzanine Gallery exhibit, Sharks! Sink Your Teeth In! on display through December 2022. 

Explore how the prehistoric past, natural environments, and maritime heritage come to life and tell a unique story of the Chesapeake Bay. The Calvert Marine Museum is open daily from 10 a.m. to 5 p.m., with limited capacity and a new timed entry system. Admission is $9 for adults; $7 for seniors, military with valid I.D, AAA and AARP members; $4 for children ages 5 - 12; children under 5 and museum members are admitted free. For more information about the museum, or to make a reservation for your next visit, please go to our website at www.calvertmarinemuseum.com. Keep up to date with the latest from CMM by following us on Facebook, Instagram, Twitter, and YouTube.

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Figures Attached:

21-25 Figure 1Figure 1: A Miocene baleen whale radius (flipper bone) preserving arching gouge marks on both its upper and lower surfaces.  A. Dorsal (external) view. B. Ventral (internal) view. Numbers 1-3 mark the locations where the shark teeth raked the surface of the radius. Numbers 1-1, 2-2, 3-3 correspond to bite traces made at the same time on the radius by teeth in opposing jaws. To improve contrast and highlight detail, the dark fossil whale radius was whitened with sublimed ammonium chloride. 

When a whale dies, it inverts and floats at the surface of the water due to the buildup of abdominal gases from decomposition. Scavenging sharks usually feed at the water line, occasionally lifting their heads out of the water. The flippers of the whale lie at the water line and extend outward from the body, providing an easy target for scavengers. 

From the similarity of the three bite traces on the dorsal side of the radius (Fig. 1A), we think that they were made by the same teeth during successive bite-shake events. The shark would have clenched down on the flipper firmly and then shaken its head vigorously in an attempt to cut through the bone (unsuccessfully) or to simply remove flesh. 

We do not know the order in which the three bite traces were made - 1, 2, 3 in Figure 1; or 3, 2, 1; or some other sequence. We think in the order 1, 2, 3 because bite 1 in Figure 1 would likely have resulted in the removal of some flesh covering the flipper. Following that, the shark might have re-bitten the bone at site 2, shaken its head and successfully removed more flesh before proceeding to biting and head shaking at site 3. 

There is no evidence of healing on the surface of the now-fossilized whale bone, which means that the whale (if it was alive at the time the shark bit it, which is doubtful) did not survive the encounter with the shark. 

21-25 Figure 2

Figure 2: One possible view of the origin of the bitten Miocene whale radius. The whale could also have been bloated and floating belly up at the time the shark bite traces were made. Furthermore, the bones at the end of the flipper may already have been missing and/or eaten when the shark clenched down on the whale’s radius. Original artwork by Tim Scheirer and Clarence (Shoe) Shumaker. © Calvert Marine Museum.

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