Late Cenozoic Ostracodes from the Drowned Terraces 
in the Hawaiian Islands 
John C. Holden 1 
ABSTRACT: Late Cenozoic ostracodes from extensive submarine terraces in the 
Hawaiian Islands ranging in depth from 260 to 355 fathoms resemble, in part, 
modern shallow water faunas of the Hawaiian and tropical Pacific islands. Of the 
35 species from the terraces, 13 are described as new. These are: Cytherelloidea 
monodenticulata, Bairdia kauaiensis, B. hanaumaensis, B. ritugerda, Hemicythere 
obesa, Mutilus oahuensis, M.(P) coales cens, Jugosocythereis venulosus, Quadracy- 
there hornibrooki, Loxoconcha batei, L. condyla, Cletocythereis bradyi , and 
Neocaudites terryi. 
The assemblage indicates an original shallow water environment for the terraces. 
Most of the extant species, which also occur as fossils from the terraces, live at 
depths less than 50 fathoms in present oceans, and only one is reliably reported as 
living deeper than 160 fathoms; several are known littoral forms. 
Submarine terraces occur at various depths 
on the flanks of the larger islands in the Hawai- 
ian archipelago. The central islands of Oahu, 
Molokai, Lanai, Maui, and Kahoolawe sur- 
mount a common ridge which rises abruptly 
from the Pacific Ocean floor from 2,500 fathoms 
to about 300 fathoms. The conspicuous break 
in slope at 300 fathoms marks the outer edges 
of extensively developed drowned terraces (Fig. 
A). Submarine terraces on the north side of 
Kauai at about the same depth are not as ex- 
tensively developed as those off the central is- 
lands. Deeper terraces are known down to 1,000 
fathoms in the Hawaiian Islands (Menard et 
al., 1962) but have not yet been dredged. 
This study is primarily concerned with the 
ostracode remains contained in several dredge 
hauls taken from the submarine terraces within 
the central island complex and off Kauai. While 
this is primarily a taxonomic study, Tables 1 
and 2 are given to evaluate paleoenvironments 
and thus unravel the obscure history of the 
Hawaiian Islands. Unfortunately, such evalua- 
tion is hindered by the lack of knowledge of the 
precise age of the Hawaiian fossil Ostracoda 
1 U. S. Navy Electronics Laboratory, San Diego 52, 
California. Present address: Department of Paleon- 
tology, University of California, Berkeley, California. 
Manuscript received December 2, 1965. 
and of the ecology of living Pacific ostracodes 
included in this report. 
Cursory observations of Recent samples from 
Clipperton Island and New Caledonia reveal 
no gross faunal similarities to the Hawaiian 
fossil faunas. From the limited number of Re- 
cent samples from the Hawaiian Islands it can 
be seen that only a few of the fossil species are 
presently living in that area (Table 1). Some 
specimens from the Recent stations are illustrated 
for clarity. 
Marked faunistic differences occur between 
terraces, indicating either temporal or environ- 
mental distictions. For example, station T-12 
at 308 fathoms does not contain Macrocypris 
gracilis or Loxoconchella honoluliensis, which 
are common at stations T-l, T-4, and T-7 at 
310, 280, and 297 fathoms respectively, nor 
does it contain the common Mutilzis (?) 
coalescens and the abundant Mzztilus oahuensis, 
found at station AR at 260 fathoms. 
BRIEF HISTORIC REVIEW OF THE OSTRACODA 
in the tropical pacific: The first published 
work on tropical Pacific ostracodes was that of 
G. S. Brady (1868^) in "Fonds de la mer.” 
However, only 1 species was treated in the 
central Pacific. Ostracodes from Java and Hong 
Kong were also covered in this series. Of greater 
1 
