New Zealand Journal of Marine and Freshwater Research abstracts
An early Paleogene sponge fauna, Chatham Island, New Zealand
Michelle Kelly
National Centre for Aquatic Biodiversity
and Biosecurity
National Institute of Water and Atmospheric
Research Limited
Private Bag 109 695, Newmarket
Auckland, New Zealand
email: m.kelly@niwa.co.nz
John S. Buckeridge
Earth and Oceanic Sciences (EOS) Research Institute
Auckland University of Technology
P.O. Box 92 006
Auckland, New Zealand
Abstract A late Paleocene-early Eocene (c. 60-53 Ma)
poriferan fauna, comprising hexactinellids (Class Hexactinellida), astrophorids
(Class Demospongiae: Family Astrophorida), and lithistids (“lithistid” Demospongiae)
has been identified from the Tutuiri Greensand outcropping on the north coast
of Chatham Island, New Zealand. Most of the fossils are hexactinellids, comprising
extremely delicate siliceous networks embedded in friable sandstone. The
sediment matrix within and around these skeletons contains numerous siliceous
demosponge spicules, many of which are exceptionally well preserved. The
soft friable matrix of the Tutuiri Greensand has made extraction a relatively
simple process, making taxonomic identification of the material, and comparison
with adjacent Recent and other New Zealand Eocene faunas possible. These
sponge body fossils and spicule microfossils indicate a fauna that was once
dominated by hexactinellids, lithistid, and astrophorid demosponges. A qualitative
comparison of the abundance and diversity of the Tutuiri Greensand sponge
fauna with the present-day Chatham Rise sponge fauna indicates that the late
Paleocene-early Eocene fauna is as diverse as the Recent fauna, for the hexactinellid
sponges and astrophorid demosponges, and much more diverse for lithistid
sponges. The paleoecology of the Tutuiri Greensand has been interpreted as
inner to mid shelf water depths (50-250 m) but the poriferan fauna described
here is more like that of the present-day soft sediment benthic environment
of the Chatham Rise at 800-1200 m.
Keywords Porifera; Hexactinellida; Demospongiae; lithistid;
Paleocene; Eocene; paleobathymetry; Tutuiri Greensand; Oamaru Diatomite;
Chatham Rise; Chatham Island
M04127; Online publication date 17 June 2005 Received 19 July 2004; accepted
14 February 2005
New Zealand Journal of Marine and Freshwater Research, 2005, Vol. 39:
899-914
0028-8330/05/3904-0899 © The Royal Society of New Zealand 2005
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