AM. ZOOLOGIST, 7:223-232 (1967).
Multiple Character Analysis of Canis lupus, latrans, and familiaris,
With a Discussion of the Relationships of Canis niger
Museum of Comparative Zoology, Harvard University,
and
WILLIAM H. BOSSERT, Department of Biology, Harvard University,
Cambridge, Mass.
BARBARA LAWRENCE,
SYNOPSIS. A multiple character analysis was undertaken of a broadly representative sample
of three species: Cants lupus (wolf), C. latrans (coyote), and C. familiaris (dog). These species
are clearly and siirnificantly distinguished by the technique of linear discrimination. The analysis provides a basis for the identification of skulls not obviously distinguishable by size or other
diagnostic characters.
Early populations of Canis n. niger and C. n. gregoryi (red wolf) are compared with the three
species above and are found to form a cluster with lupus and to be sharply distinct from the
other two species. Additional comparisons show that while lupus lycaon and niger both overlap
with lupus, they are distinct from each other. This entire cluster is quite distinct from latrans,
with niger being the farthest removed. A sample population of C. n. gregoiyi, from the edge of
the extending range of C. latrans, was examined and found to show too great a range of variation to be attributed to a single species.
With the advent of white man in North
America and his consequent modification
of the environment by lumbering and
clearing for farming, coyotes have been extending their range (Young and Jackson,
1951). As they have extended their range,
on the fringes of their newly acquired territories, animals which are difficult to identify have frequently been captured. In the
South, as often as not, these are called red
wolves, in the Northeast, coydogs. In both
parts of the country these animals occur
where coyotes have moved into areas that
formerly were inhabited by small races of
wolf. Coincident also with these shifts in
distribution has been an upward revision
in the reported weights for coyotes. Young
and Jackson (1951), eliminating a few outsized individuals, give a range of 18-30
pounds for typical western coyotes, while
Burt (1946) gives a range of 23-50 pounds
for Michigan coyotes. The latter overlaps
with weights of a long series of wolves from
Algonquin Provincial Park (unpublished
data from the Ontario Department of
Lands and Forests) and, as a result, size
alone becomes a less useful criterion in distinguishing between wolves and coyotes.
In the following discussion, since Canis
lupus, the wolf, and Canis latrans, the coyote, are both composite species, these names
as used in the text refer to each species as
a unit. When a particular subspecies is referred to, a trinomial is used, as Canis lupus lycaon. Canis niger, the red wolf, is
usually considered to include three subspecies. Their status is uncertain, and Canis niger as used in the present work refers
to the typical form, C. n. niger, and to those
southeastern populations, presently called
C. n. gregoryi, which show no evidence of
hybridization and which were collected
from well outside the range of latrans. Canis familiaris, the dog, presents no problem because, in spite of its variability, it is
monotypic.
The present study was undertaken because attempts to identify skulls of the
northeastern population of rather largesized members of the genus Canis bogged
down in a mass of overlapping characters.
It was then decided that before such fringe
populations could be identified we needed
to know what, if any, combinations of
characters reliably separated known Canis
lupus, latrans, and familiaris, particularly
if size were eliminated as a character. This
part of the work will be described in detail
in section I.
While these three species are unquestionably distinct, the red wolf, currently called
Canis niger, is a more problematical entity
and will be discussed in section II in the
light of our findings in section I.
(223)
224
BARBARA LAWRENCE AND WILLIAM H. BOSSERT
SECTION i
The purpose of this part of the study
was to determine what, if any, combinations of characters separate the three species, C. lupuSj C. latrans, and C. familiaris,
and how widely they are separated. To do
this, we have used a biased random selection of 20 adult members, including males
and females, of each species. In latrans,
wide geographic distribution within the
original range of the species was an important factor in choice of specimens. In lupus, only North American races were used
and large individuals were avoided. In familiaris, the selection was deliberately biased to include the most wolf-like and coyote-like animals.
Characters to be used were not randomly
selected but chosen because of their known
value in distinguishing the species involved. Forty-two different measurements
(see appendix) were taken on as many as
225 skulls. The measurements of 125 of
these were then variously plotted to estimate regression lines. Based on these, 24
possibly significant characters were selected,
13 dealing with skull shape and 11 with
tooth form, to test for diagnostic value.
Since we wished to ascertain whether or
not, regardless of size, skulls of each of the
species had certain unique characters or
combinations of characters, size was eliminated as a factor by relating all measurements to total length of skull. The mean
and standard deviation of these 24 characters, as a fraction of total length, were computed for each of the selected series.
The value of each character in distinguishing a pair of species was tested by
computing single character distances for
the pair, dividing the difference in means
for the two populations by the average
standard deviation.
From this analysis, nine cranial and six
tooth measurements were found to be most
diagnostic, although no single character
was found without overlap between a pair
of species. These were the measurements
used in our linear discrimination.
In the following non-numerical description of differences between the species considered, the numbers of the measurements,
which are expressions of these differences,
and which were used in our linear discrimination, are given in parentheses. For descriptions of the measurements see Appendix A.
When lupus and latrans are compared,
it is found that the most significant differences are in the relative development of
the rostrum and of the brain case. Wolves
have a relatively small brain case and massive rostrum. The latter is presumably a
reflection of the large size of the animals
on which they prey. Breadth of palate (7,
19), large teeth (11, 12, 13, 15, 20), and
heavy maxilla (8), all contribute to the
formation of powerful jaws. The position
of the anterior root to the zygomatic arch
and its massiveness help to buttress the
teeth and strengthen the crushing action
of the jaws. In the intermediate region of
the skull, the strength of the masticatory
apparatus shows in the depth of the jugal
bone (18) and in the size of the temporal
fossa. The one provides attachment for the
masseter muscle, the other space for the
temporal muscle. This space is difficult to
measure, but the relation between the
broadly spreading zygomatic arches (4) and
the narrow brain case (6) expresses it well.
Size of the temporal muscle is also shown
by the development of a large sagittal crest.
Coyotes, preying as they do on small species, have opposite skull proportions and
small, narrow teeth. Compared with the
brain case, the rostrum is slender, the maxilla and the anterior root of the zygomatic
arch less massive, the temporal fossa smaller, and the jugal narrower. All of this gives
the skull a rather long slender appearance
as compared with that of a wolf. This overall distinction is a good one and has often
been used as diagnostic in separating wolf
and coyote skulls, but it can be confusing.
Ratios of total length to zygomatic
breadth in long, narrow, wolf skulls may
overlap with these ratios for short, broad,
coyote skulls. If width of the brain case,
width across molars, and width between
premolars anteriorly are also taken into account, the characteristic, relatively-small
brain case of a typical wolf skull is immediately apparent.
MULTIPLE CHARACTER ANALYSIS OF Canis
Dogs present a different problem. Essentially they are small wolves, distinguishable
from coyotes by many of the wolf-like proportions of rostrum and brain case. However, their great variability means that no
single set of characters is equally diagnostic for all kinds. Key characters for separating lupus and latrans are based on a certain intraspecific homogeneity which is not
too difficult to describe or to see. C. familiaris lacks this homogeneity and often superficially resembles either of the other two
more than it does other familiaris. This
means that the best combinations of characters to be used for purposes of identification vary depending on whether the animal
in question is large and wolf-like or smaller and coyote-like. Certain of the highly
modified breeds are, of course, easily identified by the disproportionate development
of brain case or rostrum. Other less modified forms may be distinguished by the inflation of the frontal sinuses and resultant
steep angle of the forehead. They may also
be recognized by a bend in the mid-region
of the skull so that rostrum and brain case
meet at more of an angle than is usual in
wild canids.
Turning to the less modified kinds, and
these include many mongrels, the large
dogs differ from wolves in having relatively
small teeth, and having the skull elongated
in the interorbital region so that the distance between the tooth row and the bulla
(2) is long compared with the length of the
tooth row (10). The palate also is elongated so that its posterior margin lies well
posterior to m-. The brain case often looks
atypically heavily ossified. The sagittal
crest is usually drawn out less far beyond
the occiput; when it is strongly developed
and projecting, the dorsal margin usually
curves strongly down at the tip. Briefly,
big dogs look rather as if they had outgrown themselves and were never meant to
be that size.
For the most part, wolf-like proportions
of brain case and rostrum distinguish most
dogs from coyotes. Long, narrow-skulled
dogs may approach coyotes in some of their
length-breadth proportions, but not in all
225
of them, and a coyote-like elongation of the
tooth row is not usually accompanied by
coyote-like proportions of the teeth.
Disparate proportions of the teeth which
show as differences in certain of them also
help to distinguish dogs and coyotes. The
relatively greater size of the canine (13) in
dogs may be a reflection of their relationship with wolves. The greater width across
the incisors (15) is partly an expression of
larger tooth size; however, it also expresses
the greater premaxillary width of dogs. In
contrast, the last upper molar is small (14).
This tooth, as frequently happens with the
anteriormost or posteriormost of the cheek
teeth, is the most variable tooth in the upper jaw. Nevertheless, its average smaller
size in dogs than in wolves and coyotes is a
good diagnostic feature and may be one of
the results of domestication. The last character to be considered is characteristic of
most coyotes and is one of the best expressions of the general narrowing of the premolars and carnassials in this form. The
posterior part of p^- (22) is relatively long
compared both to the length of the tooth
(20) and to its maximum width. Because of
this lengthening, a second accessory cusp
behind the main cusp is usually present in
coyotes and has often been used as diagnostic (Gidley, 1913).
We have applied the technique of linear
discrimination as described by Kendall
(1946). Jolicoeur (1959), who has used linear discrimination to somewhat different
ends, gives an excellent graphical explanation of the technique. The computations
were done on an IBM 7094 computer using
the BIMD 05 program developed by the
University of California at Los Angeles
Medical School. In short, the technique
finds the weighted sum of a number of
characters which is most different for two
populations, that is, the weighted sum of
characters which best separates the populations. The sum itself is called the discriminant function, and the weights, determined
by the computations, are called the discriminant coefficients. The mean value of
the discriminant function for each of the
populations can be obtained by multiply-
226
BARBARA LAWRENCE AND WILLIAM H. BOSSERT
ing the mean value of each character over
the population by the discriminant coefficient for the character and then summing.
If an individual is known to belong to one
of a pair of populations, he can be identified by evaluating the discriminant function separating the pair for his values of
the characters (that is, summing the
weighted measurements for the specimen)
and assigning him to the population having the closest mean value of the function.
The accuracy of the identification will depend, of course, on the degree to which the
populations are separated by the discriminant function. A useful measure of the
multiple character difference between two
populations is the D2 statistic of Mahalonobis (see Rao, 1952). This is a general
extension of the distance comparisons for
single characters mentioned earlier.
For this study the discriminant coefficients and the D2 statistic for each pair of
the selected populations of C. latrans, lupus, and familiaris were computed using
the fifteen characters discussed above. The
discriminant coefficients are given in Table
1 along with the mean values of the disTABLE 1. Results of pairwisc discriminant analysis
for C. latrans, lupus, and familiaris.
Discriminant coefficient
lupus vs.
latrans vs.
lupus vs.
Measurements* latrans
familiaris
familiaris
2
4
6
7
8
10
11
12
13
20
22
14
15
18
3.389
— 7.107
14.971
— 0.495
— 7.313
9.889
14.984
— 12.510
—24.891
—32.167
87.360
3.652
— 8.932
3.299
1.230
19
Average discriminant function
value for latraiu! 4.79
3.10
for lupus
for familiaris
64.1 (8.0)
D= (D)
— 16.876
14.670
— 11.182
— 11.246
—33.699
—24.989
66.749
—25.968
—77.655
5.155
35.272
63.729
—28.702
31.510
— 15.404
— 6.900
8.494
— 6.760
— 5.124
— 7.849
— 10.108
26.784
— 1.089
— 4.088
22.738
—33.076
0.606
— 3.531
0.784
— 10.638
— 14.6
-14
— 4.73
— 17.8
119.9(10.9)
criminant functions for the populations, D2
and D. The last value is roughly the difference in standard deviations between the
mean values of the function for the two
populations. We see that latrans differs by
eight and nearly 11 standard deviations
from lupus and familiaris, respectively,
while lupus and familiaris differ by only a
little more than five.
A clear view of the degree of separation
of the populations achieved by the discriminant functions results from the a posteriori identification of the original individual specimens using the functions. For
each of the pairwise discriminations the
specimens were assigned to one species tentatively. A final identification was then
made by assigning the specimen to that
species for which two tentative assignments
had been made. For example, if between
latrans and lupus the specimen was assigned to lupus, between latrans and familiaris to latrans, and between lupus and
familiaris to lupus, then the specimen was
identified as lupus. In this way all sixty of
the specimens were unambiguously and
correctly identified; there was no overlap
in the values of the various discriminant
functions for the populations on which
they were based. Figure 1 gives a plot of
the populations using the la trans-lupus and
la trans-fa mi liar is discriminant functions as
— 5.44
27.2 (5.2)
* Measurements are numbered as in Appendix.
Each must be divided by total length of skull,
measurement 1.
-15
-16
-17
-18
'
FIG. 1. Linear discrimination of C. latrans (C),
C. lupus (W), and C. familiaris (D). The contours
indicate the extreme range of individuals in the
populations used. The latrans-familiaris discriminant function is used as the abscissa and the latrans-lupus discriminant function is used as ordinate.
MULTIPLE CHARACTER ANALYSIS OF Cnnis
coordinate axes. This figure shows the relative separations of the populations as well
as the lack of overlap.
SECTION n
As stated earlier, in North America, in
addition to C. lupus and C. latrans, a third
species of wild Canis, C. niger, the red
wolf, is currently recognized. Young and
Goldman (1944) describe it as a wolf which
is somewhat intermediate between lupus
and latrans, with a distribution limited to
the south-eastern part of the United States.
This is a unique situation since all other
wolves in both Eurasia (Pocock, 1935) and
North America are races of C. lupus.
Ranges as plotted for lupus and niger by
Young and Goldman (1944) show an overlapping of lupus with niger in the southeastern part of the former's range. Even
more surprising is the overlapping of all
three species of Canis at the western edge
of the range of niger and the eastern edge
of that of latrans (Young and Jackson,
1951; Young and Goldman. 1944). Such an
occurrence together of three closely related
members of the genus Canis is without
parallel elsewhere in the world. The situation is obviously peculiar, and various authors have attempted to explain it. It is
not pertinent here to review these discussions; suffice it to say that for the most part
they have concentrated on the relationship
between niger and latrans. The most recent effort to unravel the problem is a
paper by McCarley which includes an interesting discussion of the possibility of hybridization and population replacement
(1962) where latrans is encroaching on the
range of niger.
Implicit in McCarley's interpretation of
his data, though not explicitly stated, is the
fact that, while closely related species usually differ most from each other where their
ranges meet or overlap, the opposite is true
of these forms in Che south-central states.
Here, at the western edge of the range of
niger, the small C. n. rufus Audubon and
Bachman 1851 is often difficult to tell from
C. latrans jrustror Woodhouse 1851, while
at the eastern end of its range, the larger C.
n. niger Bartram 1791 is said to resemble C.
227
lupus lycaon Schreber 1775 (Young and
Goldman, 1944). Essentially, as presently
defined, niger appears as a population intermediate in characters between a large
western latrans and a small eastern lupus.
Efforts to determine the true status of
niger will be helped if we first understand
some of its taxonomic history. Because of
the complications of priority, Canis rufus
from Texas with three subspecies of increasing size from west to east now figures
in the literature as Canis niger of Florida
with three subspecies of decreasing size
from east to west. The three related forms
are the same in each case, but depending
on which end of the range one starts from,
the reasons for the primary distinction of
the species are different. Canis rufus as a
Texas phenomenon had a quite different
reason for being set apart than did Canis
niger as a Florida phenomenon. The earliest descriptions of a small wolf in the
south-central states are based on the occurrence of a medium-sized non-coyote in eastern Texas. Animals were found which resembled coyotes in size but not in cranial
characters, and the difference in size between these animals and the big plains
wolves was so great that the two were
scarcely compared. Typical coyotes were
also found to occur in the same area. The
fact that two distinct kinds of Canis were
recognized is more important than the reasons why the name rufus was selected for
the one and frustror for the other (Young
and Goldman, 1944; Young and Jackson,
1951). Once rufus was set apart as a distinct species of wolf, efforts were made to
determine the eastern limits of its range. A
reasonable number of specimens was available from Louisiana, but progressing towards Florida the number of available
specimens diminishes rapidly. There are
very few from that part of the range where
niger and lupus lycaon supposedly meet.
Since, in addition to this, there are almost
no extant specimens of C. lupus lycaon
from the southeastern states, it is easy to
see why the relationship between the eastern red wolf, C. n. niger, and C. lupus lycaon has not been more thoroughly analyzed.
228
BARBARA LAWRENCE AND WILLIAM H. BOSSERT
If the study of the small wolves in the
southern states had begun with niger in
Florida and been based on adequate series,
it is highly unlikely that niger ever would
have been separated as a species from lupus.
The biologically difficult problem of reconciling the existence of two similarlysized forms of wolf in one continuous habitat would never have arisen and the area
of systematic uncertainty would have been
more properly limited to the eastern edge
of the coyote's extending range.
The purpose of this part of the present
work has been to establish whether or not
two distinct species of wolf occur in the
southeastern United States. The following
discussion presents our evidence for considering that the wolves of this area all belong to the species lupus and that niger is
not a distinct species. Unequivocal establishment of the status of niger has seemed
a necessary preliminary to understanding
and identifying the widely varying populations from west of the Mississippi presently
identified as n. gregoryi Goldman 1937 and
n. rufus.
In order to be as certain as possible that
we were excluding latrans from our sample
population, the series selected for a linear
discrimination was limited to all available
specimens of C. n. niger and C. n. gregoryi
collected before 1920 from Louisiana, Alabama, and Florida; in addition, a Florida
skull previously identified as C. lupus lycaon was included. In the following discussion this series is referred to as C. niger.
The type of floridanus Miller 1912 ( = niger), though it could not be included because the skull is too broken, falls within
the range of variation of the rest of the
series.
In our linear discrimination, comparison
was made with the broadly representative
series of the three species, lupus, latrans,
and familiaris, used in the first section. It
was also made with a series of ten males
and ten females, all adult, of Canis lupus
lycaon, the race whose range has been presumed to overlap with that of niger in the
Southeast. The individuals were randomly
selected from 71 specimens from Algonquin
Provincial Park in Canada and weighed
from 48-81 pounds (average 58). It was necessary to use a northern population because adequate series from farther south
were not preserved before wolves were exterminated.
To the eye, the specimens of niger studied appear lupus-like and this is borne out
by the numerical analysis. As a first step
in the analysis, all of the individual specimens in the niger and lycaon populations
were identified using the discriminant functions presented in the previous section. All
were assigned to the lupus category; they
were on the whole both less coyote-like and
less dog-like than the original lupus population. In itself this provides little information about the relationships of lupus to
these populations, of course, since the identification tacitly assumes the individuals to
be from the latrans, lupus, or familiaris
groups. The study was continued, therefore, by computing the discriminant function coefficients and D2 values for all pairs
of the five populations. The values of D2
are given in Table 2. Using these with the
TABLE 2. The generalized distance, V, between populations described in the text.
C. lupus
C. latrans
64.1 C. lupus
C. familiaris
119.9
C. lupus lycaon 69.5
C. niger
116.0
27.2 C.fatniliaris
10.0
66.6
20.3
87.6
c
lui)us
lycaon
56.0
cluster grouping technique discussed by
Rao (1952), the lycaon and niger populations form a cluster with the selected lupus
population. The average D2 within this
cluster is 28.8, while the average D2 of its
members to populations outside the cluster
is 71.8. Although the lycaon and niger
populations are fairly distinct, they are
even more distant from the latrans and familiaris species groups, and have a common
similarity to the lupus population. These
relationships are shown fairly well in Figure 2, the plot of the populations using the
latrans-lycaon and lycaon-niger discriminant functions as coordinate axes. The latter axis provides maximum separation of
the wolf populations. Notice that the lu-
MULTIPLE CHARACTER ANALYSIS OF
"11
13
14
15
FIG. 2. Linear discrimination of C. latrans (C), C.
lupus (W), C. lupus lycaon (A), and C. niger (N).
The lycaon-niger discriminant function is used as
the abscissa and the latrans-lycaon discriminant
function is used as ordinate.
_L
12
229
Canis
13
J_
14
15
FIG. 3. Evaluation of discriminant functions for
the series of C. niger gregoryi from Fallsville, Arkansas. The coordinate axes are identical to those
of Figure 2.
DISCUSSION
have used a few specific measurements such
as width between the premolar teeth anteriorly, or have relied on standard lengthbreadth comparisons of the whole skull as,
for instance, relation of zygomatic width to
total length. Such data are useful but show
too much overlap to separate reliably the
species involved. They are also inadequate
as an expression of the basic differences between the skulls. These basic differences
center around the differential development
of different segments of the skull which, in
their extreme form, are easily seen. Brain
case, rostral, and interorbital shape of a
typical coyote are quite different from
those of a typical wolf. The significance of
cranial measurements in expressing these
differences in proportion depends on the
multiple relationships of each measurement with a number of others, when size
has been eliminated as a factor. The technique of linear discrimination has allowed
us to make use of these multiple relationships in comparing skulls. The results of
these comparisons showed that all three
species are sharply distinct, with lupus and
familiaris resembling each other more than
either does latrans.
Since size has been eliminated as a character, the numerical values of the discriminant function may show two skulls to be
most closely related which on the basis of
size alone would be easy to tell apart. The
same may be true of other unmeasurable
but diagnostic characters.
To date most efforts to measure differences between wolf, coyote, and dog skulls
Often, of course, there is little difficulty
in distinguishing between the three species
pus population falls intermediate to, and
completely bridges, the gap between lycaon
and niger.
Although we did not include recently
collected specimens of red wolf from Louisiana in our linear discrimination, the
relative position of each individual specimen was computed and, while found to be
clearly wolf, the specimens were spread
somewhat over the range from niger to lycaon.
It now appears that the early populations
described as Canis niger and n. gregoryi
from the southeastern wooded regions, east
of the range of Canis latrans, are a local
form of Canis lupus, not a distinct species
of wolf. The situation in the areas where
these small wolves and the large coyote,
C. I. frustror, meet is much more confused.
The present study has not attempted to go
beyond McCarley's conclusions (1962). We
have, however, tested our methods on a
small series from Fallsville, Newton County, Arkansas. The specimens, collected in
1921 and identified as Canis niger gregoryi
(Young and Goldman, 1944), span the
whole range of variation from coyote to
wolf. Figure 3 shows this variation of the
individuals using the latrans-lycaon and
lycaon-niger discriminant function as coordinate axes, as in Figure 2.
230
BARBARA LAWRENCE AND WILLIAM H. BOSSERT
without resort to the kind of analysis described above. In addition to differences
already discussed in the text, certain spot
differences are often highly diagnostic: flattened, rugose bullae characterize dogs. Coyotes have the dorso-posterior part of the
brain case well inflated, with the maximum
width of brain case in the region of the
parieto-temporal suture, the frontal shield
not tilted up, and the postorbital constriction close to the postorbital processes. In
wolves and dogs, the maximum width of
the brain case is usually at the roots of the
zygoma; the frontal shield tilts up, and the
postorbital region is elongated, so that the
constriction at the anterior part of the
brain case and that behind the postorbital
processes are well separated and the area
between inflated. Further accentuating the
different appearance of this region is the
fact that the dorsal surface of the brain case
in wolves and dogs is lower relative to the
postorbital processes than in coyotes. The
orbit in coyotes tends to be large; this
shows both in vertical dimensions and in
its length as compared to that of the zygomatic arch. In coyotes also, as distinct from
dogs and wolves, there is a round protuberance of the occiput, often thin-walled, over
the vermis of the cerebellum; certain differences in the teeth, though not precisely
measurable, are also rather diagnostic.
These are well reviewed in Young and
Jackson (1951) and will not be repeated
here. In addition, the present authors have
found useful the fact that in coyotes Mmeasured lateromedially has the distance
from the outer border of the tooth to the
base of the paracone less than the distance
from this point to the inner margin of the
tooth, while the reverse is true in wolves
and dogs. Wear makes this a difficult measurement to take precisely, but the difference, expressing as it does the plumper
para- and metacones of wolves and dogs, is
a significant one. None of these characters
is completely reliable, just as is none of
those described earlier. Used in combination, and with total size included, they are
adequate to identify most canids.
The significance of the present study lies
in the fact that linear discrimination, based
on characters tested for their diagnostic
value, can separate similarly-sized individuals of each of the three species considered.
A corollary of this is the fact that a small
wolf does not assume the characters of a
large coyote, nor is the reverse true. Criteria have been observed and tested which
distinguish the two species and these may
be used to separate individuals which approach each other in size. This has made
possible a re-examination of the specific
status of the red wolf, long a biologicallypuzzling phenomenon. From the evidence
at hand, it appears that from central Louisiana east to Florida the large canids hitherto called C. niger and niger gregoryi are
no more than subspecifically distinct from
Canis lupus. Preliminary study of a small
sample from the western part of the red
wolf's range shows typical lupus and typical
latrans both present, with the possibility of
hybridization as McCarley has suggested.
In investigating this possibility, we can now
assume that we are considering only two
species of wild canid, not three as has been
previously supposed, and that we have overlapping and possible hybridization of these
two distinct species, not an intergrading
from coyote to wolf across the southern
states as has sometimes been postulated.
Our test analysis of the Fallsville specimens
has also confirmed what has been apparent
for a long time, that cranial variation in
localized series currently called C. niger
gregoryi or C. niger rufus is atypically wide
for a race of North American Canis. Not
only is it greater than the range for a local
population of a given subspecies of either
lupus or latrans, but it is also wider than
the range for either species taken as a
whole. Either this means sympatry of locally similar forms which have the same
chromosome number and essentially similar
karyograms (Benirschke and Low, 1965;
Hungerford and Snyder, 1966), or it means
hybridization. Before this can be decided,
both the morphological and the behavioral
characteristics of these populations need to
be studied in more detail.
APPENDIX A
Following are listed the 42 measurements
MULTIPLE CHARACTER ANALYSIS OF Canis
taken on the entire series. In the first paragraph are given the 24 tested for diagnostic value. The 16 of these used in our linear discrimination are italicized. In the second paragraph is a briefer listing of the remaining 18 characters, which were found to
be not taxonomically reliable.
Skull. 1. Total length from sagittal crest
to alveoli of I—; 2. Minimum distance from
alveolus of M- to depression in front of
bulla at base of styloid process; 3. Minimum length of rostrum from orbital margin to alveolus of I-; 4. Zygomatic width;
5. Breadth across postorbital processes; 6.
Maximum breadth of brain case at parietotemporal suture; 7. Maximum crown width
across upper cheek teeth; 8. Minimum distance taken at right angles from alveolar
tnargin of molars to orbit; 9. Maximum diameter of orbit, parallel to medial edge and
starting at most ventral point; 10. Crown
length of upper cheek teeth from C - M-;
11. Crown length of P— externally; 12. Minimum crown width of P— taken between
roots; 13. Maximum antero-posterior width
of upper canine taken at base of enamel;
14. Crown width of M-; 15. Crown width
across upper incisors; 16. Height of brain
case vertical to basi-sphenoid and not including sagittal crest; 17. Maximum width
across occipital condyles; 18. Minimum
height of jugal at right angles to axis of
bone; 19. Minimum width between alveoli
of P-. Lower jaw. 20. Crown length of P-;
21. Maximum crown width of P-; 22.
Length of posterior cusps of P-, along line
parallel to base from back of tooth to point
below notch posterior to main cusp; 23.
Crown length of M- parallel to main axis;
24. Maximum crown width of M— at right
angles to main axis.
Skull. Condylo-basal length; palatal
length; length of brain case; interorbital
width; width of rostrum; width of nasals;
height of nasal aperture; alveolar length of
upper cheek teeth; alveolar length of P-;
maximum width of P- anteriorly; antero-
231
posterior diameter of I-; height of bullae;
height of posterior bony nares. Lower jaw.
Total length; distance from back of tooth
row to condyle; alveolar length P— - M—;
alveolar length C - M-; crown length C M-.
3
ACKNOWLEDGMENTS
The authors are indebted to Mr. John L. Paradiso of the United States National Museum, Dr.
George B. Kolenosky oC the Ontario Department
of Lands and Forests, Dr. Douglas H. Pimlott of
the University of Toronto, and Dr. Claude Minguy
of the Department of Fish and Game of the Province of Quebec for making available much important material.
This work has been supported by National Science Foundation Grant GB-1265. Computer time
was supported by National Science Foundation
Grant GP-2723.
REFERENCES
Benirschke, K., and R. J. Low. 1965. Chromosome
complement of the coyote (Canis latrans). Mammalian Chromosomes Newsletter No. 15, arranged
by the Section of Cytology, The Univ. of Texas,
M. D. Anderson Hospital and Tumor Institute,
Houston, Texas, p. 102, 1 fig.
Burt, W. H. 1946. The mammals of Michigan.
Univ. of Michigan Press, Ann Arbor, xv -f. 288
p., illustr.
Gidley, J. W. 1913. Preliminary report on a recently discovered Pleistocene cave deposit near Cumberland, Maryland. Proc. U. S. Natl. Mus. 46:93102, figs. l-8a.
Goldman, E. A. 1937. The wolves of North America. J. Mammal. 18:37-45.
Hungerford, D. A., and R. L. Snyder. 1966. Chromosomes of a European wolf (Canis lupus) and a
bactrian camel (Camelus bactrianus). Mammalian Chromosomes Newsletter No. 20, arranged
by the Section of Cytology, The Univ. of Texas,
M. D. Anderson Hospital and Tumor Institute,
Houston, Texas, p. 72-73, 1 fig.
Jolicoeur, P. 1959. Multivariate geographical variation in the wolf Canis lupus L. Evolution 13:
283-299.
Kendall, M. G. 1951. The advanced theory of statistics, Vol. II. Hafner House, New York. 521 p.
McCarley, H. 1962. The taxonomic status of wild
Canis (Canidae) in the South Central United
States. The Southwestern Naturalist 7:227-235.
Pocock, R. I. 1935. The races of Canis lupus. Proc.
Zool. Soc. London, part 3:647-686, 2 pis.
232
BARBARA LAWRENCE AND WILLIAM H. BOSSERT
Rao, C. R. 1952. Advanced statistical methods in
biometric research. John Wiley, New York. 390
p.
Young, S. P., and E. A. Goldman. 1944. The wolves
of North America. The American Wildlife Insti-
tute, xx -f 636 p., illustr.
Young, S. P., and H. H. T. Jackson. 1951. The
clever coyote. The Stackpole Co., Harrisburg,
Pa., and The Wildlife Management Institute,
Washington, D. C. xv -(- 411 p., illustr.