phylogenetic relationships and classification of didelphid marsupials ...

2009 VOSS AND JANSA: DIDELPHID MARSUPIALS 165
Character 59: Interparietal absent (0); or present (1).
See text for a discussion of this character and its
taxonomic distribution.
Character 60: Interparietal and supraoccipital separated
by an open suture, at least in juvenile specimens
(0); or interparietal-supraoccipital suture fused in
juveniles and adults (1). See text for a discussion of
this character, which was scored as inapplicable
(‘‘-’’) for taxa lacking an interparietal, and as missing
(‘‘?’’) for taxa in which it is not known whether
an interparietal is present or absent (see above).
Character 61: Parietal-mastoid contact present (0); or
absent (1). See text for a discussion of this
character and its taxonomic distribution.
Character 62: ‘‘Accessory’’ fenestrae absent (0); or
present (1). These nonvascular openings (first
apparently named by Lyne and Mort, 1981: 124)
perforate the maxillary palate at the level of P1
and/or P2, occupying a position in between the
incisive foramina and the maxillopalatine fenestrae.
In the context of this study, state 1 is an
autapomorphy of Perameles.
Character 63: Maxillopalatine fenestrae absent (0); or
present (1). This character was modified from its
original formulation (Voss and Jansa, 2003:
character 38) by eliminating an intermediate state
for polymorphism, which was recoded as 0/1 for
this analysis. See text for comments about traits
expressed by outgroup taxa.
Character 64: Left and right maxillopalatine fenestrae
separated by a median septum (0); or confluent,
septum absent (1). See text for a discussion of this
character and its taxonomic distribution.
Character 65: Palatine fenestrae absent (0); or present
(1). Scoring criteria and information about the
distribution of these traits among didelphid terminals
were provided by Voss and Jansa (2003:
character 39). See text for comments about traits
expressed by outgroup taxa.
Character 66: Maxillary fenestrae absent (0); or
present (1). Scoring criteria and information about
the distribution of these traits among didelphid
terminals were provided by Voss and Jansa (2003:
character 40). See text for comments about traits
expressed by outgroup taxa.
Character 67: Posterolateral palatal foramina present,
with complete bony margins (0); or absent, bony
margins incomplete, represented by open notches in
posterolateral palate (1). See text for a discussion
of this character and its taxonomic distribution.
Character 68: Posterolateral palatal foramina posterior
to fourth molars (0); or extending lingual to M4
protocones (1). Scoring criteria and information
about the distribution of these traits among
didelphid terminals were provided by Voss and
Jansa (2003: character 41). See text for comments
about traits expressed by outgroup taxa. Although
posterolateral palatal foramina are coded as absent
in dasyurids, their position behind the M4 protocones
in those taxa is indicated by the open notches
mentioned in the preceding character description.
Character 69: Posterior palate without distinct lateral
corners, the choanae unconstricted behind (0); or
posterior palate with distinct lateral corners, choanae
constricted (1). Descriptions of the states of this
character have been slightly reworded from their
original phrasing in Voss and Jansa (2003: character
42), where the distribution of these traits was
described for didelphid terminals. See text for
comments about traits expressed by outgroup taxa.
Character 70: Presphenoid exposed in roof of nasopharyngeal
orifice above posterior palatal margin (0);
or presphenoid concealed by vomer above posterior
palatal margin (1). See text for a discussion of this
character and its taxonomic distribution.
Character 71: Left and right pterygoids separate (0);
or in midline contact and forming a sagittal keel (1).
See text for a discussion of this character and its
taxonomic distribution.
Character 72: Transverse canal foramen absent (0); or
present (1). Scoring criteria and information about
the distribution of these traits among didelphid
terminals were provided by Voss and Jansa (2003:
character 44). See text for comments about traits
expressed by outgroup taxa.
Character 73: Extracranial course of mandibular nerve
not enclosed by bone (0); or consistently enclosed by
anteromedial strut of alisphenoid bulla (1); or
usually enclosed by posteromedial bullar lamina
(2). Scoring criteria and information about the
distribution of these traits among didelphid terminals
were provided by Voss and Jansa (2003:
character 45). See text for comments about traits
expressed by outgroup taxa. In the absence of any
compelling evidence for intermediacy among these
alternative conditions, this character was treated as
unordered in all of our analyses.
Character 74: Alisphenoid tympanic process and rostral
tympanic process of petrosal separated by a distinct
gap (0); or in contact (1). See text for a discussion
of this character and its taxonomic distribution.
Character 75: Epitympanic recess small, snugly enclosing
the mallear-incudal joint (0); or inflated, arching
high above mallear-incudal joint (1). See text for a
discussion of this character and its taxonomic
distribution.
Character 76: Rostral and caudal tympanic processes of
petrosal separated by a distinct gap (0); or in
contact and separated by a suture (1); or indistinguishably
fused (2). States 0 and 1 of this character
represent the same pattern of ingroup variation
that Voss and Jansa (2003: character 47) described
in terms of concealment of the fenestra cochleae.
See text for comments about traits expressed by
outgroup taxa. Because state 1 is plausibly
intermediate to states 0 and 2, this character was
treated as ordered (0 « 1 « 2) in all of our
analyses.
Character 77: Squamosal epitympanic sinus absent (0);
or present (1). See text for a discussion of this
character and its taxonomic distribution.
Character 78: Anterior limb of ectotympanic directly
attached to skull (0); or indirectly attached via
malleus (1). Scoring criteria and information about
the distribution of these traits among didelphid
terminals were provided by Voss and Jansa (2003:
character 46). See text for comments about traits
expressed by outgroup taxa.
Character 79: Ectotympanic laterally exposed (0); or
concealed from lateral view inside bulla (1). See text