557 Early Pliocene fish remains from Arctic Canada support a pre-Pleistocene dispersal of percids (Teleostei: Perciformes) Alison M. Murray, Stephen L. Cumbaa, C. Richard Harington, Gerald R. Smith, and Natalia Rybczynski Abstract: Percid remains from Pliocene deposits on Ellesmere Island, Arctic Canada, are identified as a species of Sander, similar to the walleye and sauger of North America and the pike–perch of Europe and western Asia. They are named as a new species, Sander teneri. These remains are the most northerly percid elements found to date and suggest the palaeoen- vironment was significantly warmer in the Pliocene than it is currently. The fossil remains show the presence in North America of the family Percidae as well as the genus Sander prior to the Pleistocene, indicating a previously proposed Pleistocene immigration from Europe or Asia can be discounted. These fossils contradict an earlier hypothesis that percids, in particular Sander, crossed from Eurasia to North America in the Pleistocene; instead, the fossils show percids were al- ready in the area by the Pliocene. Re´sume´ : Des restes de percide´s provenant de de´poˆts plioce`nes de l’ıˆle Ellesmere, dans l’Arctique canadien, sont attribue´s a` une espe`ce de Sander semblable au dore´ jaune et au dore´ noir d’Ame´rique du Nord, et au sandre d’Europe et d’Asie oc- cidentale. Le nouveau nom d’espe`ce Sander teneri leur est attribue´. Ces restes constituent les e´le´ments de percide´s les plus nordiques trouve´sa` ce jour et portent a` croire que le pale´omilieu e´tait sensiblement plus chaud au Plioce`ne qu’il ne l’est actuellement. Les restes fossiles de´montrent que la famille des Percide´sdemeˆme que le genre Sander e´taient pre´sents en Ame´rique du Nord avant le Ple´istoce`ne, ce qui invalide la the`se ante´rieurement propose´e d’une immigration ple´istoce`ne provenant d’Europe ou d’Asie. L’existence de ces fossiles vient contredire une hypothe`se ante´rieure voulant que les per- cide´s, et plus particulie`rement Sander, soient arrive´s en Ame´rique du Nord en provenance de l’Eurasie au Ple´istoce`ne. Les fossiles montrent plutoˆt que les percide´se´taient de´ja` pre´sents en Ame´rique du Nord durant le Plioce`ne. [Traduit par la Re´daction] Introduction 2001; Tedford and Harington 2003). However, the beaver remains belong to the extinct Dipoides, and further evidence A unique locality in the Canadian Arctic has produced a is lacking to indicate this genus was a dam-builder (Rybc- number of fossil remains of a small perciform fish. The lo- zynski 2008). cality, south of the head of Strathcona Fiord on Ellesmere Island in Nunavut (Fig. 1), preserves as peat the organic Although it is possible that the small beaver periodically sediment that accumulated in a pond in the early Pliocene dammed the stream, allowing a small lake or pond to form, (Harington 2001; Tedford and Harington 2003). Named the the water apparently was occasionally drained by a break in Beaver Pond site, the sediments are possibly the result of the dam (C.R. Harington, personal observation, 2006). Many beaver activity, as an accumulation of intertwined beaver- specimens are relatively complete and in a fine state of pres- cut sticks, mainly aligned northwest–southeast in a matrix ervation. The perciform fish probably would not have lived in of silty sand and cobbles, might represent part of a beaver bog conditions but could have been in the body of freshwater dam and beaver remains including a partial skeleton have that occupied the area for relatively long periods, which are been recovered from the site (C.R. Harington, field notes, marked by silty stringers between peat layers in the stratigra- phy (C.R. Harington, personal observation, 2006). The Beaver Pond site, currently thought to date between 5 Received 23 March 2009. Accepted 31 July 2009. Published on and 4 Ma (Tedford and Harington 2003), preserves remains the NRC Research Press Web site at cjes.nrc.ca on of mammals that indicate an interchange of fauna between 16 September 2009. Asia and North America that probably occurred prior to Paper handled by Associate Editor H.-D. Sues. *5 million years ago (Tedford and Harington 2003; Daw- son and Harington 2007). This locality, above 788N latitude, A.M. Murray.1 Department of Biological Sciences, University is the only known North American Pliocene vertebrate site of Alberta, Edmonton, AB T6G 2E9, Canada. north of 558N latitude (Dawson and Harington 2007). S.L. Cumbaa, C.R. Harington, and N. Rybczynski. Canadian Museum of Nature, P.O. Box 3443, Station D, Ottawa, ON K1P 6P4, Canada. Geological setting G.R. Smith. Fish Division, Museum of Zoology, University of The Beaver Pond site at 78831’N, 82822’W, at an elevation Michigan, Ann Arbor, MI 48109-1079, USA. of 378 m, is located south of the head of Strathcona Fiord. 1Corresponding author (e-mail: [email protected]). This is one of many late Tertiary fossiliferous sites on Elles- Can. J. Earth Sci. 46: 557–570 (2009) doi:10.1139/E09-037 Published by NRC Research Press 558 Can. J. Earth Sci. Vol. 46, 2009 Fig. 1. Location of the Beaver Pond site marked with a star. (A) Map of the lands around the Arctic Circle with Ellesmere Island labelled; (B) Ellesmere Island showing the location of Bay Fiord; (C) location of the Beaver Pond site at the southeast end of Bay Fiord. mere Island referred to as the ‘‘high terrace sequence.’’ Typi- associated with one another or the 1992 specimen, and at cally found high on valley sides, these unconsolidated depos- least one (a cleithrum) may be a distinct species from the its unconformably overlie the Late Cretaceous to early 1992 individual. However, all the bones recovered belong Tertiary Eureka Sound Group. They are capped with glacial to perciform fishes. deposits and were presumably deposited prior to significant landscape downcutting (Mathews and Fyles 2000). The Bea- Comparisons with other species ver Pond site occurs within a high terrace deposit that is an The most diagnostic fossil elements from Strathcona *30–40 m thick unit of mostly sands and gravels. The site Fiord, particularly the cleithra and anguloarticular itself appears to be a slump block (see Mathews and Ovenden bones, were compared with a diversity of perciform species, 1990) derived from a peat layer that occurs *5 m below the including those that currently inhabit freshwaters of Canada capping glacial till. The elevation of the hill crest above the and the United States, as well as perciforms found in eastern site is *402 m. The fossil beds and associated beds above Asia (Siberia) and Europe, and additional marine or fresh and below the locality are all freshwater, as indicated by sili- water taxa (e.g., Lates) that are morphologically similar. ceous microfossils (Harington 2001), with no indication of in- Most of the comparative material examined (Appendix A) terbedded marine sequences in the vicinity. consists of prepared, dried skeletons with a few exceptions Discovered in 1961, the site was not intensively excavated being cleared and stained material or fossil material as noted until 1992. For the following 10 years, most collection ef- in Appendix A. forts were focussed on the northeast end of the site, where the mossy peat unit was originally *2.4 m thick. The Bea- Estimation of body size ver Pond site as currently excavated (in 2006) is 7 m across To estimate the body size of the fossil specimen, linear re- section facing towards the southeast. The stratigraphy, as de- gression was performed using the approach of Casteel (1976). termined in 2006 (Fig. 2A), is variable across section, indi- We used log-base 10 anterior centrum width regressed against cating a complex depositional history. The fish remains log-base 10 standard length on the second anterior vertebra in reported here were recovered from the peat unit at the north- 10 specimens of Sander canadensis of known size in the col- east end of the site (Fig. 2B). lections of the Canadian Museum of Nature. Material and methods Institutional abbreviations CMN, Canadian Museum of Nature, Ottawa, Ontario; Fossil material FMNH, Field Museum of Natural History, Chicago, Illinois; The perciform elements were collected by C.R. Harington ROM, Royal Ontario Museum, Toronto, Ontario; UAMZ, and colleagues in 1992 and 1995. The elements collected in University of Alberta Museum of Zoology, Edmonton, Al- 1992 (CMN 53270), discovered by John Tener, were all as- berta; UMMZ, University of Michigan Museum of Zoology, sociated in a single, small bolus of fibrous peat located Ann Arbor, Michigan. within 20 cm of the base of the a peat layer, some 60 cm from the northeastern end of the site, and seemed to repre- sent a small individual fish identified in the field as ‘‘Per- Systematic palaeontology cidae?’’ (C.R. Harington, field notes, 1992). Other elements Superorder Acanthopterygii (sensu Johnson and Patterson, collected in 1995 (CMN 52226, 52230, and 53271) are not 1993) Published by NRC Research Press Murray et al. 559 Fig. 2. (A) Stratigraphy of the Beaver Pond site excavation as it appeared at the end of the 2006 field season. The right side of the section is toward the northeast. The star shows the estimated location of the type specimen (Canadian Museum of Nature (CMN) 53270) of the new taxon collected in 1992. (B) Photograph of the site in 1993. The fossil fish remains were collected from the area indicated by the arrow. Series Percomorpha Rosen, 1973 vitreus has 0–6 spines, usually none, which are weaker than Order Perciformes Bleeker, 1859 in S.