[Palaeontology, 2017, pp. 1–8]
RAPID COMMUNICATION
THE OLDEST MARINE VERTEBRATE FOSSIL FROM THE VOLCANIC ISLAND OF ICELAND: A PARTIAL RIGHT WHALE SKULL FROM THE HIGH LATITUDE PLIOCENE TJORNES€ FORMATION by DANIEL J. FIELD1,7 , ROBERT BOESSENECKER2,3,RACHELA. RACICOT4,5,LOV ISA ASBJ ORNSD€ OTTIR 6,KRISTJAN JONASSON 6,ALLISONY. HSIANG1,ADAMD.BEHLKE1,7 and JAKOB VINTHER1,8,9 1Department of Geology & Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA; [email protected], [email protected] 2Department of Geology & Environmental Geosciences, College of Charleston, Charleston, SC 29424, USA; [email protected] 3University of California Museum of Paleontology, University of California, Berkeley, CA 94720, USA 4The Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA 90007, USA; [email protected] 5Smithsonian Institution, PO Box 37012, MRC 121, Washington, DC 20013–7012, USA 6Icelandic Museum of Natural History, Reykjav ık, Iceland 7Current address: Milner Centre for Evolution, Department of Biology & Biochemistry, University of Bath, Bath, BA2 7AY, UK; danieljaredfi[email protected] 8Current address: Denver Museum of Nature and Science, 2001 Colorado Blvd, Denver, CO 80205, USA 9Current address: School of Earth Sciences & Biological Sciences, University of Bristol, Bristol, UK; [email protected]
Typescript received 5 August 2016; accepted in revised form 3 December 2016
Abstract: Extant baleen whales (Cetacea, Mysticeti) are a marine sedimentary outcrop. The specimen is diagnosed as disparate and species-rich group, but little is known about a partial skull from a large right whale (Mysticeti, Balaeni- their fossil record in the northernmost Atlantic Ocean, a dae). This discovery highlights the Tjornes€ Formation as a region that supports considerable extant cetacean diversity. potentially productive fossil vertebrate locality. Addition- Iceland’s geographical setting, dividing North Atlantic and ally, this find indicates that right whales (Eubalaena) and Arctic waters, renders it ideally situated to shed light on bowhead whales (Balaena) were sympatric, with broadly cetacean evolution in this region. However, as a volcanic overlapping latitudinal ranges in the Pliocene, in contrast island, Iceland exhibits very little marine sedimentary to the modern latitudinal separation of their living coun- exposure, and fossil whales from Iceland older than the terparts. late Pleistocene are virtually unknown. Here, we present the first fossil whale found in situ from the Pliocene Key words: Balaenidae, Iceland, Pliocene, biogeography, Tjornes€ Formation (c. 4.5 Ma), Iceland’s only substantial marine mammal, Tjornes.€
M UCH of the lower Tjornes€ Formation of northern Ice- exposure. Fieldwork in the Tjornes€ Formation in the land dates from the early Pliocene (Buchardt & S ımonar- summer of 2011 revealed a partial skull of a mysticete son 2003). This important period in cetacean whale. This study diagnoses the fossil and describes its evolutionary history documents the first appearance of stratigraphical setting to enable estimation of its temporal many modern taxa that coexisted with archaic species and environmental context. that have since gone extinct (Fordyce & Barnes 1994). We identify the fossil as a partial skull of a right whale This geological period also has the potential to fill in gaps (Balaenidae, cf. Eubalaena). Our find represents the twen- in the historical biogeographical record for extant ceta- tieth balaenid fossil diagnosable to genus level from the cean subclades (Whitmore 1994; Fordyce 2002; Boesse- North Atlantic and Mediterranean, and we provide a necker 2013). Here, we report findings from the first complete list reviewing the previously described material. vertebrate palaeontological expedition to the Tjornes€ For- The recovery of a right whale (Eubalaena) from this high- mation, Iceland’s only substantial marine sedimentary latitude Pliocene locality, combined with records of
© The Palaeontological Association doi: 10.1111/pala.12275 1 2 PALAEONTOLOGY bowhead whales (Balaena) in similarly-aged sediments at lower latitudes, suggests that these two balaenid taxa may have been sympatric during this temporal interval, in contrast to their allopatric modern distributions. The identification of the Tjornes€ Formation as a marine mammal-bearing locality makes it one of only a small handful of high-latitude Pliocene localities worldwide that have produced marine mammals; future exploration of this locality may yield additional Pliocene marine mam- mals of biogeographical significance.
GEOLOGICAL SETTING
Overview of Tj€ornes Geology
The fossil was discovered in a cliff on the west-facing edge of the Tjornes€ Peninsula, in north-eastern Iceland (66°000– 66°120N, 16°570–17°240W; Fig. 1). Four major lithological units are found on the Tjornes€ Peninsula (Fig. 1): the Ter- tiary Kaldakv ısl lavas, Tjornes€ beds, Hoskuldsv€ ık lavas, and the Quaternary Bredav ık Group (Eir ıksson 1981; Buchardt &S