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The Early Origin of the Antarctic Marine Fauna and Its Evolutionary Implications.

Crame JA, Beu AG, Ineson JR, Francis JE, Whittle RJ, Bowman VC - PLoS ONE (2014)

Bottom Line: The extensive Late Cretaceous - Early Paleogene sedimentary succession of Seymour Island, N.E.It is also possible that the marked Early Paleogene expansion of neogastropods in Antarctica is in part due to a global increase in rates of origination following the K/Pg mass extinction event.Evolutionary source - sink dynamics may have been significantly different between the Paleogene greenhouse and Neogene icehouse worlds.

View Article: PubMed Central - PubMed

Affiliation: British Antarctic Survey, Natural Environment Research Council, Cambridge, United Kingdom.

ABSTRACT
The extensive Late Cretaceous - Early Paleogene sedimentary succession of Seymour Island, N.E. Antarctic Peninsula offers an unparalleled opportunity to examine the evolutionary origins of a modern polar marine fauna. Some 38 modern Southern Ocean molluscan genera (26 gastropods and 12 bivalves), representing approximately 18% of the total modern benthic molluscan fauna, can now be traced back through at least part of this sequence. As noted elsewhere in the world, the balance of the molluscan fauna changes sharply across the Cretaceous - Paleogene (K/Pg) boundary, with gastropods subsequently becoming more diverse than bivalves. A major reason for this is a significant radiation of the Neogastropoda, which today forms one of the most diverse clades in the sea. Buccinoidea is the dominant neogastropod superfamily in both the Paleocene Sobral Formation (SF) (56% of neogastropod genera) and Early - Middle Eocene La Meseta Formation (LMF) (47%), with the Conoidea (25%) being prominent for the first time in the latter. This radiation of Neogastropoda is linked to a significant pulse of global warming that reached at least 65°S, and terminates abruptly in the upper LMF in an extinction event that most likely heralds the onset of global cooling. It is also possible that the marked Early Paleogene expansion of neogastropods in Antarctica is in part due to a global increase in rates of origination following the K/Pg mass extinction event. The radiation of this and other clades at ∼65°S indicates that Antarctica was not necessarily an evolutionary refugium, or sink, in the Early - Middle Eocene. Evolutionary source - sink dynamics may have been significantly different between the Paleogene greenhouse and Neogene icehouse worlds.

No MeSH data available.


Related in: MedlinePlus

Geological and locality map for Seymour Island, north-eastern Antarctic Peninsula.Roman numerals within the La Meseta Formation indicate Telms 1–7; Telm 4 is a very thin unit that can be traced intermittently along the boundary between Telms 3 and 5. KPB =  Cretaceous/Paleogene boundary. Further details on stratigraphic nomenclature are contained in the text and S1 Appendix. Based on Montes et al [117], with modifications. Cross Valley lies between López de Bertodano Bay and Penguin Bay.
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pone-0114743-g001: Geological and locality map for Seymour Island, north-eastern Antarctic Peninsula.Roman numerals within the La Meseta Formation indicate Telms 1–7; Telm 4 is a very thin unit that can be traced intermittently along the boundary between Telms 3 and 5. KPB =  Cretaceous/Paleogene boundary. Further details on stratigraphic nomenclature are contained in the text and S1 Appendix. Based on Montes et al [117], with modifications. Cross Valley lies between López de Bertodano Bay and Penguin Bay.

Mentions: A series of recent studies has clarified that a number of key components of the modern Antarctic marine fauna were in place well before the onset of global cooling in the late Middle Eocene. This is particularly so within the marine invertebrates where significant elements of the numerically dominant Mollusca occur in the fossil record as much as 20 m.y. before the initial stages of cooling at ∼42 Ma [1], [2]. The critical faunas on which these findings are based are all from Seymour Island at the north-eastern tip of the Antarctic Peninsula (Fig. 1) where excellent vertical and lateral exposure has allowed unprecedented access to Late Cretaceous – Early Paleogene marine faunas and floras at a high paleolatitude (∼65°S) [3]–[7]. Since the initial discovery of these representatives of the modern Antarctic marine fauna, work has continued to refine both their taxonomic affinities and relative biostratigraphical positions. A number of new occurrences of modern Antarctic taxa in the fossil record have been recognised and it is important to place these and all previous records in as accurate a stratigraphical framework as possible. Within this highly fossiliferous locality it should be possible to match faunal trends and patterns directly with changes in paleoclimates and paleoenvironments. Is the introduction of elements of the modern fauna in some way linked to the aftermath of the mass extinction event at the Cretaceous – Paleogene (K/Pg) boundary, or perhaps to paleoclimatic events such as Early – Middle Eocene global warming? Are there elements within the fauna that might help us to determine whether Antarctica acted as an evolutionary source or sink during the Early Cenozoic?


The Early Origin of the Antarctic Marine Fauna and Its Evolutionary Implications.

Crame JA, Beu AG, Ineson JR, Francis JE, Whittle RJ, Bowman VC - PLoS ONE (2014)

Geological and locality map for Seymour Island, north-eastern Antarctic Peninsula.Roman numerals within the La Meseta Formation indicate Telms 1–7; Telm 4 is a very thin unit that can be traced intermittently along the boundary between Telms 3 and 5. KPB =  Cretaceous/Paleogene boundary. Further details on stratigraphic nomenclature are contained in the text and S1 Appendix. Based on Montes et al [117], with modifications. Cross Valley lies between López de Bertodano Bay and Penguin Bay.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4262473&req=5

pone-0114743-g001: Geological and locality map for Seymour Island, north-eastern Antarctic Peninsula.Roman numerals within the La Meseta Formation indicate Telms 1–7; Telm 4 is a very thin unit that can be traced intermittently along the boundary between Telms 3 and 5. KPB =  Cretaceous/Paleogene boundary. Further details on stratigraphic nomenclature are contained in the text and S1 Appendix. Based on Montes et al [117], with modifications. Cross Valley lies between López de Bertodano Bay and Penguin Bay.
Mentions: A series of recent studies has clarified that a number of key components of the modern Antarctic marine fauna were in place well before the onset of global cooling in the late Middle Eocene. This is particularly so within the marine invertebrates where significant elements of the numerically dominant Mollusca occur in the fossil record as much as 20 m.y. before the initial stages of cooling at ∼42 Ma [1], [2]. The critical faunas on which these findings are based are all from Seymour Island at the north-eastern tip of the Antarctic Peninsula (Fig. 1) where excellent vertical and lateral exposure has allowed unprecedented access to Late Cretaceous – Early Paleogene marine faunas and floras at a high paleolatitude (∼65°S) [3]–[7]. Since the initial discovery of these representatives of the modern Antarctic marine fauna, work has continued to refine both their taxonomic affinities and relative biostratigraphical positions. A number of new occurrences of modern Antarctic taxa in the fossil record have been recognised and it is important to place these and all previous records in as accurate a stratigraphical framework as possible. Within this highly fossiliferous locality it should be possible to match faunal trends and patterns directly with changes in paleoclimates and paleoenvironments. Is the introduction of elements of the modern fauna in some way linked to the aftermath of the mass extinction event at the Cretaceous – Paleogene (K/Pg) boundary, or perhaps to paleoclimatic events such as Early – Middle Eocene global warming? Are there elements within the fauna that might help us to determine whether Antarctica acted as an evolutionary source or sink during the Early Cenozoic?

Bottom Line: The extensive Late Cretaceous - Early Paleogene sedimentary succession of Seymour Island, N.E.It is also possible that the marked Early Paleogene expansion of neogastropods in Antarctica is in part due to a global increase in rates of origination following the K/Pg mass extinction event.Evolutionary source - sink dynamics may have been significantly different between the Paleogene greenhouse and Neogene icehouse worlds.

View Article: PubMed Central - PubMed

Affiliation: British Antarctic Survey, Natural Environment Research Council, Cambridge, United Kingdom.

ABSTRACT
The extensive Late Cretaceous - Early Paleogene sedimentary succession of Seymour Island, N.E. Antarctic Peninsula offers an unparalleled opportunity to examine the evolutionary origins of a modern polar marine fauna. Some 38 modern Southern Ocean molluscan genera (26 gastropods and 12 bivalves), representing approximately 18% of the total modern benthic molluscan fauna, can now be traced back through at least part of this sequence. As noted elsewhere in the world, the balance of the molluscan fauna changes sharply across the Cretaceous - Paleogene (K/Pg) boundary, with gastropods subsequently becoming more diverse than bivalves. A major reason for this is a significant radiation of the Neogastropoda, which today forms one of the most diverse clades in the sea. Buccinoidea is the dominant neogastropod superfamily in both the Paleocene Sobral Formation (SF) (56% of neogastropod genera) and Early - Middle Eocene La Meseta Formation (LMF) (47%), with the Conoidea (25%) being prominent for the first time in the latter. This radiation of Neogastropoda is linked to a significant pulse of global warming that reached at least 65°S, and terminates abruptly in the upper LMF in an extinction event that most likely heralds the onset of global cooling. It is also possible that the marked Early Paleogene expansion of neogastropods in Antarctica is in part due to a global increase in rates of origination following the K/Pg mass extinction event. The radiation of this and other clades at ∼65°S indicates that Antarctica was not necessarily an evolutionary refugium, or sink, in the Early - Middle Eocene. Evolutionary source - sink dynamics may have been significantly different between the Paleogene greenhouse and Neogene icehouse worlds.

No MeSH data available.


Related in: MedlinePlus