Fish and tetrapod communities across a marine to brackish salinity gradient in the Pennsylvanian (early Moscovian) Minto Formation of New Brunswick, Canada, and their palaeoecological and palaeogeographical implications

O Gogain, A. and Falcon-Lang, H. J. and Carpenter, D. K. and Miller, R. F. and Benton, M. J. and Pufahl, P. K. and Ruta, M. and Davies, T. G. and Hinds, S. J. and Stimson, M. R. (2016) Fish and tetrapod communities across a marine to brackish salinity gradient in the Pennsylvanian (early Moscovian) Minto Formation of New Brunswick, Canada, and their palaeoecological and palaeogeographical implications. Palaeontology, 59 (5). pp. 689-724. ISSN 0031-0239

Documents
Minto%20fish%20DRAFT%20DC%208%20FEB_MR.docx

Request a copy
24634.pdf
[img]
[Download]
[img] Microsoft Word
Minto%20fish%20DRAFT%20DC%208%20FEB_MR.docx - Whole Document
Restricted to Repository staff only

182kB
[img]
Preview
PDF
24634.pdf - Whole Document

916kB
Item Type:Article
Item Status:Live Archive

Abstract

Euryhaline adaptations in Pennsylvanian vertebrates allowed them to inhabit the marine to freshwater spectrum. This is illustrated by new assemblages of fish and tetrapods from the early Moscovian Minto Formation of New Brunswick, Canada. Fish include chondrichthyans (xenacanthids and the enigmatic Ageleodus), acanthodians (gyracanthids and acanthodiforms), sarcopterygians (rhizodontids, megalichthyids and dipnoans), and actinopterygians (eurynotiforms). Tetrapods include small- to medium-sized, and largely aquatic, stem tetrapods (colosteids) and anthracosaurs (embolomeres). A key finding is that the parautochthonous fossil assemblages are preserved across a salinity gradient, with diversity (measured by the Simpson Index) declining from open marine environments, through brackish embayments, and reaching a nadir in tidal estuaries. Chondrichthyans dominate the entire salinity spectrum (65% of fossils), a distribution that demonstrates a euryhaline mode of life, and one large predatory chondrichthyan, Orthacanthus, may have practised filial cannibalism in coastal nurseries because its heteropolar coprolites contain juvenile xenacanthid teeth. In contrast, other fish communities were more common in open marine settings while tetrapods were more common in coastal brackish waters. While all these faunas were also likely to have been euryhaline, their osmoregulation was, perhaps, less versatile. The demonstration of widespread euryhalinity among fish and aquatic tetrapods explains why Pennsylvanian faunas generally show a cosmopolitan biogeography because taxa were able to disperse via seaways. It also resolves the paradox of enriched strontium isotopic signatures observed in these faunas because organisms would have been, at times, exposed to continental water bodies as well. Therefore, our new findings contribute to the long-running debate about the ecology of Pennsylvanian fishes and tetrapods.

Keywords:Pennsylvanian, fish communities, salinity gradient, euryhaline, cosmopolitan, New Brunswick, NotOAChecked
Subjects:C Biological Sciences > C180 Ecology
C Biological Sciences > C182 Evolution
F Physical Sciences > F641 Palaeontology
C Biological Sciences > C160 Marine/Freshwater Biology
C Biological Sciences > C181 Biodiversity
Divisions:College of Science > School of Life Sciences
Related URLs:
ID Code:24634
Deposited On:09 Oct 2016 19:32

Repository Staff Only: item control page