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A NEW FOSSIL TORTOISE FROM MONA ISLAND, WEST INDIES,
AND A TENTATIVE ARRANGEMENT OF THE
TORTOISES OF THE WORLD

A NEW FOSSIL TORTOISE FROM MONA
ISLAND, WEST INDIES, AND A TENTATIVE ARRANGEMENT OF THE
TORTOISES OFTHE WORLD

ERNEST WILLIAMS
Harvard University

BULLETIN
OF THE
AMERICAN MUSEUM OF NATURAL HISTORY
NEW YORK 1952
VOLUME 99 : ARTICLE 9

BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY
Volume 99, article 9, pages 541-560, text figures 1-4,
plates 44-47, table 1
Issued November 10, 1952

Price: $.50 a copy

INTRODUCTION
X 1926 Dr. H. E. Anthony and Mr. G. G.
oodwin, exploringthe caves and phosphate
-posits of Mona Island, between Puerto
ico and Hispaniola, for fossil mammals, ob.mned remains of a peculiar tortoise that
*oves to be a new and distinct form, the prese relationships of which are uncertain. This
,w tortoise is best assigned to the genus
estudo as broadly interpreted, but it is difrent enough to receive a new subgeneric
Lme.1
The island from which thenew tortoise
imes has been well described by K. P.
-hmidt (1926), and to his paper the reader
referred for information regarding the deils of its topography and its known verte*ate faunas. No turtles are found on it
day, and only nine species of Recent rep.es.
The island is an arid limestone mass 62
iles long and 4 miles wide, honeycombed
ith caves and with sheer cliff walls on three
les.It is probably the remnant of a formerly
uch larger island and perhaps the relict of
former land connection between Puerto
ico and Hispaniola.
The greater number of fragments of the
,w tortoise come from Lirio Cave, which has
,en described by Anthony (MS) as a "vast
-twork of intercommunicating caverns...
series of chambers which frequently lead to
l outlook on the sea and with manyopengs through the ceiling through which enter
e roots of the jaguey tree."
Material in this cave was preserved in a
ddish clay which immediately over the
rface of most of the bones is modified into a
nestone film of varying thickness but of
Liformly resistant character. The bones
!re apparently much eroded and weathered
fore preservation. The few bones not
vered by a limestone film areexcessively
oded. No elements are articulated, and
veral individuals are represented. Such shell
.rts as exist are in general very thin, cometely shattered, and have nowhere sepa-

rated along a suture. Land shells were encrusted on many of the bones.
It is assumed that these tortoises fell into
the cave through the fissures in the roof.
Their bones then shattered, weathered, and
disintegratedunless they were preserved by
the formation of a lime deposit over the surfaces.
The dissociated nature of the fragments of
course raises the question of the propriety of
their reference to a single form. Several iMdividuals of very different sizes are certainly
represented. However, all the duplicated
parts are reasonably congruent.
As with all terrestrial West Indian fossils
it isdifficult to establish the age of the new
tortoise. In this as in most other instances the
suspicion exists that the remains are barely
to be considered fossil and are sub-Recent
rather than Pleistocene. There are, however,
few grounds for any opinion.
All the bones are fresh and unmineralized.
Most of those from Lirio Cave are covered by
a limestone deposit, but the few elements
from othercaves and phosphate deposits
have the appearance of weathered fresh bone.
The associated fauna is of little assistance.
Fragments of a large iguana (Cyclura sp.)
and of the rodent tlsolobodon portoricensis2
were found in the various caves and deposits
but not in direct association with the turtle
remains. They would not in any case imply
antiquity; a species of Cyclura still lives on...