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laterally from the side of the cranium [1]. Defined by Barnes (2006:42, character 63),
the derived character state is present in
Platanista gangetica,
for which see
illustrations published by Van Beneden & Gervais (1868-1880: pl. XXXI, Figures 2,
2a, 9, 9a); by Kellogg (1924:pl. 5); and Figures 11A and 11B herein.
64.
Tympanosquamosal recess, or fossa for middle sinus:
no fossa developed for
middle sinus [0]; or fossa is present [1]. This fossa, called the tympano-squamosal
recess (Fraser and Purves, 1960; and see Fordyce, 1994), in the living animal is a
recess in the bone that marks the location of the middle sinus (see Barnes, 1990:21,
node 10; 2006:42, character 64), which is a branch of the middle ear sinus system.
The fossa is on the ventral surface of the squamosal bone between the ear region and
the medial margin of the glenoid fossa on the ventral surface of the squamosal (see
for example Fraser and Purves, 1960:pls. 17-18; and Figure 11C herein, where it is
shown on specimens of
Platanista gangetica).
R
ESULTS
No Mysticeti were included in the analysis.
Zygorhiza
is represented in this analysis by
the Late Eocene North American relatively derived archaeocete,
Zygorhiza kochii,
and this
member of the archaeocete family Basilosauridae serves in the present analysis to root the
phylogenetic tree.
Agorophius
is represented by the Late Oligocene
Agorophius pygmaeus
(see images and characters in Fordyce, 1981) and this stem odontocete, which was not
included in the (1994) analysis by Fordyce, serves as the outgroup, and helps to demonstrate
the polarity of the characters of Platanistoidea.
Morphological characters that we list for
Squalodon,
a taxon that was included in the
(1994) analysis by Fordyce, were based on
Squalodon
as reported by Muizon (1988a, 1988b,
& 1994), on
S.
calvertensis
as reported by Kellogg (1923), and on
S.
calvertensis
and
S.
whitmorei
as reported by Dooley (2005).
Notocetus
is based on
Notocetus
vanbenedeni,
and it
also represents the characters of
Squalodelphis,
a closely related genus in the family
Squalodelphinidae (Muizon, 1987; Fordyce, 2006).
Zarhachis flagellator
serves to represent
the characters of the derived pomatodelphinine platanistid genus
Pomatodelphis.
All characters in the analysis are binary; none are multistate. The plesiomorphic character
states were determined by outgroup comparisons with the archaeocete Zygorhiza kochii and
with the stem odontocete Agorophius pygmaeus. The numbers of the characters in the above
list are the same as those that appear in the Matrix of Character Codings (Table 1). Some
characters that are not preserved on available specimens, and thus not known for a particular
taxon, were scored on the matrix as ?. The entries with a ? are treated the same way in PAUP
(Swofford, 2002) as are characters that are known to be absent in a taxon, which in Table 1
are indicated by a dash (-). Examples of the latter are character states relating to the
premaxillary sac fossa and premaxillary foramen for Zygorhiza, because these are structures
that never evolved in the Archaeoceti.
The phylogenetic analysis presented here includes the 64 characters that are listed and
defined above, and that were scored for nine taxa. Figure 12 shows the only tree that was
generated by PAUP from a manipulation of the data in Table 1 using MacClade (Version
3.1.1; Maddison and Maddison, 1992).
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