Redescription of the skull of Ummulisani rutgersensis Gaffney, Tong, and Meylan, 2006, a bothremydid side-necked turtle from the Eocene of Morocco

2008·1.2 MB·English

by  Gaffney, Eugene S

A tamerican museum
Novitates
PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY
CENTRAL PARK WEST AT 79TH STREET, NEW YORK, NY 10024
Number 3615, 20 pp., 8 figures, 2 tables June 16, 2008
Redescription of the Skull of Ummulisani rutgersensis
Gaffney, Tong, and Meylan, 2006, a Bothremydid
Side-Necked Turtle from the Eocene of Morocco
EUGENE S. GAFFNEY1 AND HAIYAN TONG2
ABSTRACT
Three skulls of Ummulisani rutgersensis are described here as an addendum to the descriptions
and analyses presented in Gaffney et al. (2006a). The present paper is essentially a replacement for
the Ummulisani cranial morphology text in that paper (Gaffney et al. 2006a: 447^-57). The original
description was based primarily on one skull, AMNH 30563, the type of Ummulisani rutgersensis.
Because two previously undescribed skulls, AMNH 30569 and AMNH 30562, are more complete,
they add significantly to our understanding of this taxon. However, it does not alter the results of
the phylogenetic analysis by Gaffney et al. (2006a), in that Ummulisani rutgersensis remains the
sister taxon to Phosphatochelys tedfordi.
INTRODUCTION (2006a: appendix 1) for ease of comparison
with other bothremydids. Based on the phy¬
The Bothremydidae is an extinct group of logenetic analysis of Gaffney et al. (2006a),
side-necked turtles recently reviewed and Ummulisani rutgersensis is a member of the
expanded in content by Gaffney et al. tribe Taphrosphyini as characterized in
(2006a). The purpose of the present paper is Gaffney et al. (2006a). Figures, descriptions,
to modify and expand the description of one and references to all of the bothremydid taxa
taxon named in that paper, Ummulisani referred to in this paper can be found in
rutgersensis, by adding two specimens to the Gaffney et al. (2006a). The taxonomy also
description. The skull description follows the follows that reference. Ummulisani rutgersen¬
outline and formatting of Gaffney et al. sis is included in the data set of Gaffney et al.
1 Division of Paleontology, American Museum of Natural History ([email protected]).
2 Division of Paleontology, American Museum of Natural History, [email protected] (mailing address 16 cour
du Liegat, 75013, Paris France).
Copyright © American Museum of Natural History 2008 ISSN 0003-0082
2 AMERICAN MUSEUM NOVITATES NO. 3615
Fig. 1. Ummulisani rutgersensis Gaffney, Meylan, and Tong, 2006. AMNH 30563 holotype. Partially
restored views of skull. A, dorsal; B, ventral; C, lateral, (from Gaffney et al., 2006a) (C. Blik del.)
(2006a: appendix 3) and is shown in clado- enough to serve as the type. It is the purpose
grams in figures 288-314. The reader should of this paper to redescribe Ummulisani on the
consult this work for further discussion of this basis of all three skulls, particularly incorpo¬
phylogenetic analysis, which concluded that rating information from the more complete
Ummulisani is the sister taxon to Phospha- skulls. This present paper is essentially a
tochelys within the subtribe Taphrosphyina. replacement for the Ummulisani cranial mor¬
Ummulisani was first named and described phology text in Gaffney et al. (2006a: 447-
in 2006 by Gaffney (Gaffney et al., 2006a). 457) and should be considered an addendum
Although three skulls of this taxon were to that paper.
known at that time, only one was sufficiently Other additions to Gaffney et al. (2006a)
prepared to fully describe and figure. are Gaffney et al. (2006b), describing Aclei-
Unfortunately, that skull, the holotype and stochelys and Gaffney et al. (in prep.),
figured skull, AMNH 30563, is the least describing new Bothremys and Chedighaii
complete of the three, although complete material from North America.
2008 GAFFNEY AND TONG: REDESCRIPTION OF UMMULISANIRUTGERSENSIS 3
Fig. 2. Ummulisani rutgersensis Gaffney, Meylan, and Tong, 2006. AMNH 30563 holotype. A, dorsal; B,
ventral; C, right lateral; D, anterior; E, left lateral; F, posterior, (from Gaffney et al., 2006a) (C. Blik del.)
The type specimen of Ummulisani rutgers¬ about the locality and the stratigraphy, which
ensis, AMNH 30563 (figs. 1-3), was one of the is “Marah Iaresh, 20 km south east of Ouled
few purchased specimens from the Moroccan Ouali” (Gaffney et al. 2006a), although no
phosphates that has the original information shark-teeth dating is available. Two additional
4 AMERICAN MUSEUM NOVITATES NO. 3615
specimens, AMNH 30569 (figs. 4-6), a skull more unusual pleurodires. Ummulisani has
and plastron also from Marah Iaresh, and hornlike processes on the prefrontals, and
AMNH 30562 (figs.7, 8), an isolated skull these probably were covered by a hornlike
without precise locality information, con¬ scale that would have been larger than the
tained the original matrix, which is the white, underlying bony process in life, as in the
soft, sandy phosphate. The shark teeth found squamosal horns of meiolaniids. The phylo¬
in the matrix indicates a Ypresian (Early genetic analysis of Gaffney et al. (2006a)
Eocene) age for both (Cappetta, personal resolves Ummulisani as the sister taxon to
commun.), which agrees with the type speci¬ Phosphatochelys.
men.
Ummulisani rutgersensis Gaffney, Tong, and
Ummulisani Gaffney, Tong, and Meylan, 2006 Meylan, 2006
Type and Only Included Species: Um¬ Type Specimen: AMNH 30563, skull,
mulisani rutgersensis Gaffney, Tong, and lacking palate (figs. 1-3; Gaffney et al.,
Meylan, 2006. 2006a: figs. 206, 207), purchased from Adam
Distribution: Eocene of Morocco. Aaronson.
Etymology: Ummu- ’llhsan, Arabic, “moth¬ Type Locality: “Mrah Iaresh, 20 km
er of integrity” is the originally (Gaffney south east of Ouled Boali” (from Adam
et al., 2006:103) intended etymology. According Aaronson), Ouled Abdoun Basin, Morocco
to our present editor (M. Knight, personal (Gaffney et al., 2006a: figs. 14-16).
commun.), this was transliterated in error when Horizon: “Eocene Phosphates, Upper
the “h” was dropped from the genus name, so Ypresian, Couche O” (from Adam Aaronson);
that it may be translated as “the mother of see Gaffney et al. (2006a: 73-76, fig. 17, for
the tongue” or “the mother of language” (Ummu discussion and references to Moroccan phos¬
’l-lisan). phates).
Revised Diagnosis: A member of the tribe Depositional Environment: Near-shore
Taphrosphyini with the unique feature of a marine (see Gaffney et al., 2006a: 73-76).
hornlike, anterodorsal process on each pre¬ Diagnosis: As for genus.
frontal. Other distinguishing features are a Etymology: For Rutgers, the State
partially open septum orbitotemporale in University of New Jersey, in gratitude to the
contrast to other Taphrosphyini such as faculty of the Department of Geology,
Nigeremys and Arenila; apertura narium Rutgers College, New Brunswick, who from
externa smaller than in Rhothonemys, but 1961 to 1965 provided the senior author with
similar in size to Phosphatochelys; preorbi¬ inspiration, encouragement, and friendship, as
tal part of skull short, in contrast to well as with an education.
Taphrosphys and Labrostochelys; triturating Referred Material: AMNH 30562, skull
surface unique in having very deep labial ridge and plastron (figs. 7, 8; plastron figured
beneath orbit with very low to absent labial in Gaffney et al., 2006a: figs. 268, 269),
ridge beneath apertura narium externa; labial Couch 0, late Ypresian phosphates (based on
ridge and maxilla very thin, as in Labrosto¬ shark teeth; Cappetta, personal commun.),
chelys and in contrast to Phosphatochelys Mrah Iahresh, 20 km southeast of Ouled
and Rhothonemys', wide quadrate-basisphe- Boali, Ouled Abdoun Basin, Morocco;
noid contact, as in Taphrosphys and in AMNH 30569 (figs. 4-6), skull, Ypresian
contrast to all other Taphrosphyini; foramen phosphates (based on shark teeth; Cappetta,
posterius canalis carotici interni formed en¬ personal commun.), Ouled Abdoun Basin,
tirely by quadrate (in two of three specimens), Morocco.
as in Labrostochelys, but in contrast to all Previous Work: This taxon was first
other pleurodires. described by Gaffney et al. (2006a), which is
Discussion: This genus, now known from the only literature on the taxon to date.
three skulls, one with a plastron, is one of the Discussion: See Conclusions below.
2008 GAFFNEY AND TONG: REDESCRIPTION OF UMMULISANIRUTGERSENSIS 5
ABBREVIATIONS separated from the orbital margin by the
prefrontal-parietal contact, as in Ummulisani.
Institutional Abbreviations
Many other turtles have small frontals, but
AMNH American Museum of Natural
none combine that with large prefrontals to
History
produce a prefrontal-parietal contact.
In all three skulls there is a narrow
Anatomical Abbreviations
anterolateral contact with the dorsal process
bo basioccipital
bs basisphenoid of the maxilla. The maxilla contact in
ex exoccipital Ummulisani is about the same size and
fjp foramen jugulare posterius position as in Phosphatochelys. It is narrower
fpcci foramen posterius canalis carotici than in Taphrosphys and Azabbaremys.
interni Structures: The prefrontal in Ummu¬
fpo fenestra postotica
lisani has the midline projection seen in other
fr frontal
Taphrosphyini. It is roughly similar in size and
ica incisura columellae auris
shape to that in Phosphatochelys. However,
ju jugal
there is some variation within Ummulisani; in
mx maxilla
na nasal AMNH 30569 and AMNH 30562 the process
op opisthotic is larger and more ventrally directed than in
pa parietal AMNH 30563.
pal palatine Ummulisani is unique in having a hornlike
pf prefrontal process on the anterolateral margin of each
pm premaxilla
prefrontal. Contrary to the original descrip¬
po postorbital
tion in Gaffney et al. (2006), these processes
pr prootic
are not developed to exactly the same extent in
pt pterygoid
all three skulls. In AMNH 30569 and AMNH
qj quadratojugal
qu quadrate 30562 the horns are more massive and
so supraoccipital protrude anterodorsally to a greater extent
sq squamosal than in AMNH 30562. The anterior surface of
vo vomer the prefrontal in AMNH 30569 and AMNH
XII foramen nervi hypoglossi 30562 faces almost directly anteriorly rather
than anterodorsally as in AMNH 30563,
Cranial Morphology which makes the horns more protuberant.
(see table 1 for measurements) The horn or process is cone-shaped and lies
at the anterodorsal margin of the orbit.
Prefrontal (figs. 1, 3, 6, 8)
There is nothing similar in any other turtle.
Phosphatochelys and other Taphrosphyini do
Preservation: Both prefrontals are com¬
plete in AMNH 30563 except for a small part not even have swellings or thickened bone in
of the maxilla contact. The prefrontals in this area. The ventral surface is visible in
AMNH 30569 and AMNH 30562 are both AMNH 30563 and AMNH 30569. The
present and nearly complete. There is some prefrontal forms almost all the roof of the
breakage in AMNH 30562 on the right fossa nasalis and the major part of the sulcus
prefrontal. olfactorius.
Contacts: In AMNH 30563, the type
specimen, there is a long medial contact with Frontal (figs. 1, 3, 6, 8)
the parietal. In the two other specimens of
Ummulisani, AMNH 30569 and AMNH Preservation: The frontal is present and
30562, small paired frontals lie in the medial nearly complete in AMNH 30569 and AMNH
part of this suture and the prefrontal-parietal 30562. It is absent in AMNH 30563, but not
contact is relatively short. The only other the result of preservational damage, it was
pleurodire or turtle to have a prefrontal- absent in life, see above. Whether this was
parietal contact is Phosphatochelys. Phospha- the result of individual variation, interspecific
tochelys also has small frontals that are variation, or pathology, is not known. In
6 AMERICAN MUSEUM NOVITATES NO. 3615
Fig. 3. Ummulisani rutgersensis Gaffney, Meylan, and Tong, 2006. AMNH 30563 holotype. A, dorsal; B,
ventral; C, right lateral; D, anterior; E, left lateral; F, posterior, (from Gaffney et al., 2006a) (C. Blik del.)
AMNH 30569 the right frontal is complete, Contacts: The frontal contacts the pre¬
but the left is broken laterally and its contact frontal anterolaterally, the parietal posterior¬
with the left prefrontal is indistinct. In AMNH ly, and the other frontal medially.
30562 the frontals are complete but separated Structures: The frontal has a flat dorsal
along their sutures from the prefrontals and surface. It does not enter the orbital margin
each other. due to the prefrontal-parietal contact. On its
2008 GAFFNEY AND TONG: REDESCRIPTION OF UMMULISANIRUTGERSENSIS 7
Fig. 4. Ummulisani rutgersensis Gaffney, Meylan, and Tong, 2006. AMNH 30569. Partially restored
view of palate. (M. Vabulas del.)
ventral surface, there is a deep parasagittal In AMNH 30563 the processus inferior
ridge marking the lateral edge of the sulcus parietalis on both sides is present but slightly
olfactorius. This ridge is formed on the damaged by dorsoventral crushing that has
prefrontal in the frontalless AMNH 30563. obscured its ventral contacts. The anterior
margin of the processus is broken on both
sides. In AMNH 30569 only the right proces¬
Parietal (figs. 1, 3, 6, 8)
sus inferior parietalis is exposed, and in
Preservation: Both parietals are present AMNH 30562 both sides are covered by
in all three skulls. The right parietal of matrix.
AMNH 30562 is broken with slight displace¬ Contacts of Dorsal Plate: The large
ment of the pieces, and the left parietal of parietal of Ummulisani contacts the other
AMNH 30569 is missing some of its central parietal medially, the prefrontal anterolater-
area, which has been restored. In AMNH ally and frontal anteriorly (but see Pre¬
30563 the dorsal plate of the right parietal frontal for the frontalless AMNH 30563),
is complete except on its posterior edge. The the postorbital anterolaterally, the quadra-
left one has a broken lateral and posterior tojugal posterolaterally, and a small dorsal
margin. plate of the supraoccipital posteromedially.
AMERICAN MUSEUM NOVITATES NO. 3615
Fig. 5. Ummulisani rutgersensis Gaffney, Meylan, and Tong, 2006. AMNH 30569. A, dorsal; B, ventral;
C, right lateral; D, anterior; E, left lateral; F, posterior. (C. Facella del.)
2008 GAFFNEY AND TONG: REDESCRIPTION OF UMMULISANIRUTGERSENSIS 9
Fig. 6. Ummulisani rutgersensis Gaffney, Meylan, and Tong, 2006. AMNH 30569. A, dorsal; B, ventral;
C, right lateral; D, anterior; E, left lateral; F, posterior. (C. Facella del.)
10 AMERICAN MUSEUM NOVITATES NO. 3615
Fig. 7. Ummulisani rutgersensis Gaffney, Meylan, and Tong, 2006. AMNH 30562. A, dorsal; B, ventral;
C, right lateral; D, anterior; E, left lateral; F, posterior. (C. Facella del.)
Except for the absence of a frontal contact On the ventral surface of the dorsal plate,
in the type specimen, AMNH 30563, these AMNH 30563 lacks a complete septum
contacts are similar to those found in orbitotemporale and has a transverse ridge
Phosphatochelys. instead, marking the posterior limits of the
Structures of Dorsal Plate: The poste¬ fossa orbitalis and the dorsal position of the
rior temporal emargination in Ummulisani is septum. In AMNH 30569 and AMNH 30562
about the same as in Phosphatochelys. the septum orbitotemporale is present but in