Body Mass Estimations and Paleobiological Inferences on a New Species of Large Caracara (Aves, Falconidae) from the Late Pleistocene of Uruguay

Abstract

The caracaras belong to a group of falconids with widespread geographical distribution in the Western Hemisphere, particularly in South America. Here we report fossil remains of a new species attributed to the genus Caracara from the late Pleistocene of Uruguay. This bird would have had an estimated body mass of 3700 grams, a value that greatly exceeds the maximum body mass reported for living falconids. Apparently, it would have had flying capabilities, in contrast to another paleospecies recently described from the Holocene of Jamaica. This fossil bird was found in association with mammal megafaunal remains and could offer new insights about the role of carnivorous birds in late Pleistocene environments of South America.

Full text

BODY MASS ESTIMATIONS AND PALEOBIOLOGICAL INFERENCES ON A
NEW SPECIES OF LARGE CARACARA (AVES, FALCONIDAE) FROM THE
LATE PLEISTOCENE OF URUGUAY
WASHINGTON JONES,
1
ANDR ´
ES RINDERKNECHT,
1
RAFAEL MIGOTTO,
2
AND R. ERNESTO BLANCO
1,3
1
Museo Nacional de Historia Natural, CC. 399, 11.000, Montevideo, Uruguay, ,wawijo@yahoo.com.ar.;,apaleorinder@yahoo.com.;
2
Departamento de Zoologia, Instituto de Biociˆ
encias, Universidade de Sa
˜o Paulo, Rua do Mata
˜o travessa 14, n8321, 05508–900, Sa
˜o Paulo, Brazil,
,rmigotto@usp.br.; and
3
Instituto de F´
ısica, Facultad de Ciencias, Universidad de la Rep ´
ublica, Igua
´4225, Montevideo 11.400, Uruguay,
,ernesto@fisica.edu.uy.
ABSTRACT—The caracaras belong to a group of falconids with widespread geographical distribution in the Western
Hemisphere, particularly in South America. Here we report fossil remains of a new species attributed to the genus
Caracara from the late Pleistocene of Uruguay. This bird would have had an estimated body mass of 3700 grams, a value
that greatly exceeds the maximum body mass reported for living falconids. Apparently, it would have had flying
capabilities, in contrast to another paleospecies recently described from the Holocene of Jamaica. This fossil bird was
found in association with mammal megafaunal remains and could offer new insights about the role of carnivorous birds in
late Pleistocene environments of South America.
INTRODUCTION
CARACARAS,FOREST-FALCONS, falcons, and falconets comprise
the family Falconidae, one of the four families of the
traditional order Falconiformes, commonly referred to as the
diurnal birds of prey (White et al., 1994). The 61 species
allocated in ten genera are globally distributed except on the
Antarctic continent. Falconids occur in a variety of habitats and
exhibit a multiplicity of behaviors and body shapes, ranging
from long-winged and fast-flying predatory birds (genus Falco)
to forest inhabitants with great flight maneuverability (genus
Micrastur) and to ground-dwelling scavenging birds (genera
Caracara and Phalcoboenus). Based on a phylogenetic analysis
of syringeal morphology and molecular data, Griffiths (1999)
divided the Falconidae in two subfamilies: subfamily Herpeto-
therinae—which includes the genera Herpetotheres and Mi-
crastur–, and subfamily Falconinae. The latter includes the tribe
Caracarini with the genera Milvago,Daptrius,Ibycter,Caracara
and Phalcoboenus; and the tribe Falconini with the genera
Spiziapteryx,Falco,Microhierax and Polihierax. Attempts to
reconstruct the evolutionary biogeography of the family
suggested that the origin and early diversification of the group
may have occurred in South America (Griffiths, 1999); and most
of the diversity of extant genera (seven of 10) is concentrated in
this part of the world (Ferguson-Lees and Christie, 2001).
The living members of the genus Caracara (formerly
Polyborus, but see Banks and Dove, 1992) are represented by:
Caracara plancus from Amazon River to Peru, south to Straits
of Magellan; and Caracara cheriway from southern North
America, Cuba, Central America to northern South America
(Dove and Banks, 1999). A third and insular species, Caracara
lutosus from Guadalupe Island, became extinct in the early
twentieth century (Greenway, 1967; Dove and Banks, 1999).
The earliest record of the Falconidae family in South America
is represented by Badiostes patagonicus Ameghino, 1895 from
the early Miocene of Patagonia (Ameghino, 1895; Brodkorb,
1964). Recently, the systematic position of two early-middle
Miocene species of genus Thegornis Ameghino, 1895 was
rearranged from Accipitridae to Falconidae (Noriega et al.,
2011). There are several fossil species described from
Pleistocene–Holocene deposits of North America and West
Indies, most of which are referred to the genus Caracara.
Wetmore (1920) described Caracara latebrosus from Holocene
cave of Puerto Rico. Caracara prelutosus have been described
based on several remains from Pleistocene deposits of Rancho
La Brea, California (Howard, 1938). Caracara creightoni
Brodkorb, 1959, is another paleospecies reported from Pleisto-
cene and probable Holocene deposits of Cuba and the Bahamas
(Olson and Hilgartner, 1982; Sua
´rez and Olson, 2001, 2003;
Steadman et al., 2007). More recently, Olson (2008) described
Caracara tellustris, reported from Holocene caves of Jamaica as
a conspicuous bird characterized by the presence of several non-
flying features.
In this context, we describe herein a large specimen of a new
Caracara species from the late Pleistocene of southern Uruguay,
with a body mass estimation that exceeds the range of any
known living species of Falconidae. The material consists of a
nearly complete coracoid and femur and other skeletal elements
belonging to a single individual.
GEOLOGICAL AND BIOSTRATIGRAPHIC SETTING
The described material was recovered in southern Uruguay
(Fig. 1) in fluvial deposits of brown mudstones with calcium
carbonate concretions. A nearly complete skeleton of Glyptodon
sp. was found in association with the fossil bird material studied
here. The remains of several mammals including Glyptodon
clavipes Owen, 1839, Propraopus sp., Eutatus seguini Gervais,
1867, Lestodon sp., Toxodon sp., Macrauchenia patachonica
Owen, 1838, Cervidae indet., Lagostomus sp., Galea sp. are
summarized by Rinderknecht (2006). Rinderknecht (1998) also
reported a material of an indeterminate Colubridae from the
same site. The bearing sediments of this fauna have been
assigned to the late Pleistocene and included in Libertad
Formation (Ubilla and Rinderknecht, 2001; Rinderknecht,
2006), although based on lithography it is not possible to rule
out that they belong to Dolores Formation, also assigned to the
late Pleistocene (Ubilla and Perea, 1999; Ubilla, 1999; Mart´
ınez
and Ubilla, 2004).
MATERIALS AND METHODS
The allometric relationships obtained by Alexander (1983),
Anderson et al. (1985), and Campbell and Marcus (1992) were
appliedtoestimatebodymassesof the new taxon described here
and for Thegornis musculosus MPM-PV-3443 using femoral
measurements. From the same authors, although using tarso-
151
Journal of Paleontology, 87(1), 2013, p. 151–158
Copyright Ó2013, The Paleontological Society
0022-3360/13/0087-0151$03.00

metatarsal measurements, the body masses of Thegornis
musculosus MPM-PV-3443 and Caracara tellustris USNM
535727 were also estimated. We calculated the circumference
of an elliptical cross-section of the femoral mid-shaft of
Thegornis musculosus by using the width and deep measures
(major and minor axes respectively) at that point. The
measurements of the coracoidal sternal end width, defined as
the distance between the processus lateralis and the angulus
medialis coracoidei, were used for body mass estimation from
reduced major axis regression with log-transformed data from
28 specimens of 19 species of Falconiformes. The distance from
the coracoidal foramen (at proximal rim) to the procoracoidal
rim at the base of the procesus procoracoideus and from the
angulus medialis coracoidei to the coracoidal foramen (at
proximal rim), were measured to calculate the relative position
of the coracoidal foramen among extant Caracarini species in
comparison to the specimen described here. All measurements
were taken with dial calipers.
Taxonomic arrangement and anatomical terminology were
based on revision of Griffiths (1999) and White et al. (1994),
and Howard (1929) and Baumel and Witmer (1993) respective-
ly. Comparative specimens are listed in Appendix 1; measure-
ments are provided in Table 1 and Appendix 2; measurement
data and plot regression are provided in Appendix 2.
Institutional acronyms.—AMNH, American Museum of Nat-
ural History, New York; MHNT, Museu Historia Natural do
Taubat´
e, Sao Paulo-Brazil; MNHN, Museo Nacional de Historia
Natural, Montevideo-Uruguay; MPM-PV, Museo Regional Pro-
vincial Padre M. J. Molina, R´
ıo Gallegos, Argentina; LACMHC,
Los Angeles County Natural History Museum, U.S.A.; USNM,
National Museum of Natural History, Smithsonian Institution,
Washington D.C., U.S.A.; WS, William Sua
´rez collection, La
Habana, Cuba.
SYSTEMATIC PALEONTOLOGY
Class AVES Linnaeus, 1758
Order FALCONIFORMES (Sharpe, 1874)
Family FALCONIDAE Leach, 1820
Remarks.—The fossil material described here is referred to the
family Falconidae based on the following characters: the sternal
end of coracoid does not strongly flare out as it does in
Accipitridae, Cathartidae, Pandionidae and Saggitaridae. The
medial angle is acuted or blunt, and the processus lateralis is
rounded and thus not forming a distinct sternocoracoid process,
this being the typical condition observed in falconids (Jollie
1976).
Genus CARACARA Merrem, 1826
Remarks.—The following character states observed in the
material are typical of Caracarini representatives: 1) a wide width
of sternal end; 2) the curved shape of distal portion of the linea
intermuscularis ventralis; 3) a deep muscular impression of the m.
supracoracoideus in dorsal view; 4) the presence of a well marked
tuberculum on the processus lateralis coracoidei; 5) the medial
direction of the muscular line from the margo supra angularis in
coracoidal ventral view.
The stoutness of the coracoidal shaft of the fossil coracoid is
comparable to the observed in the species of the genus Caracara.
Concerning this particular feature, a remarkable difference occurs
between the genera Phalcoboenus and Caracara, as Phalcoboe-
nus’s coracoidal shaft is more robust and shorter than Caracara
species. This relative stoutness of the genus Phalcoboenus can
also be observed in other skeletal elements (see Olson, 2008, figs.
1–3). The ‘‘impressio musculi obturatorius’’ is large and similar in
shape to that observed in the other species of the genus Caracara.
CARACARA MAJOR new species
Figures 2–4
Diagnosis.—Remarkable great size; out-of-size range of any
known living Caracara species and only comparable with fossil
species Caracara tellustris Olson, 2008. Femoral shaft cross-
section expanded mediolaterally, lateral and medial tubercula of
muscle gastrocnemialis are leveled at the proximal border of the
fossa poplitea, in contrast to other Caracarini species, where the
FIGURE 1—Map of Uruguay with solid circle indicating the locality where
the holotype of Caracara major n. sp. (MNHN 615) was collected.
TABLE 1—Comparison of coracoidal measurements (in mm) between Caracara major n. sp. (MNHN 615) and living species of falconid (mean and range).
Species
(N¼number of specimens)
Sternal end
width (SW)
Distance of angulus
medialis to coracoidal
foramen (DAMF)
Distance of coracoidal
foramen to procoracoidal
rim (DFPR) DFPR/DAMF
Caracara major n. sp. 35.01 60.81 9.56 0.16
Caracara plancus
(N¼3)
23.78
(24.94–22.64)
44.13
(44.62–43.52)
9.97
(10.60–9.65)
0.23
(0.24–0.22)
Milvago chimango
(N¼2)
12.13
(12.58–11.67)
23.87
(24.25–23.48)
5.15
(5.33–4.96)
0.22
(0.23-0-2)
Ibycter americanus 15.71 30 6.43 0.21
Phalcoboenus australis
(N¼3)
23.63
(24.52–22.68)
43.26
(43.84–36.76)
11.91
(13.15–11.29)
0.28
(0.32–0.26)
Herpetotheres cachinnans
(N¼2)
17.18
(17.29–17.06)
35.71
(36.71–34.7)
6.85
(7.35–6.35)
0.2
(0.21–0.18)
Micrastur semitorquatus
(N¼2)
18.01
(19.09–16.92)
39.01
(42.09–35.93)
6.96
(7.90–6.01)
0.18
(0.19–0.17)
152 JOURNAL OF PALEONTOLOGY, V. 87, NO. 1, 2013

tuberculum m. gastrocnemialis lateralis is more proximally
positioned (Fig. 5); coracoidal distal end very expanded in
relation to its proximo-distal length; distance of coracoidal
foramen to procoracoidal rim shorter than the observed on other
Caracarini species (see Fig. 6).
Description.—The omal end of the coracoid is missing. There is
a coracoidal foramen rather than a coracoidal fenestra. This
condition is typically observed in Herpetotherinae and Caracarini
genera and different from the exhibited in Falconini representa-
tives (Friedmann, 1950).
In contrast to Herpetotherinae genera the procoracoidal process
of the coracoid is roughly perpendicular to the coracoidal shaft
FIGURE 2—Skeletal elements of Caracara major n. sp. (MNHN 615) from late Pleistocene of Uruguay. 1a, 1b, anterior and posterior views of left femur,
respectively; 2a, 2b, dorsal and ventral views of left coracoid, respectively; 3a, 3b, ventral and dorsal views of proximal end of right scapula, respectively; 4,
fragment of left costal margin of sternum. Scale bar¼1 cm.
FIGURE 3—Femur views of Caracara major n. sp. (MNHN 615). 1a–1d,
posterior, lateral, media1, and anterior views, respectively. Gray parts in C.
major n. sp. are reconstructed assuming geometric scaling with Caracara
plancus. Abbreviations: fos. poplit.¼fossa poplitea; impr.m. obtur.¼impression
musculi obturatorius; lin. intermusc. cran.¼linea intermuscularis cranialis;
nut.for.¼nutrient foramen; tuberc. m. gastroc. lat.¼tuberculum musculi
gastrocnemius, pars lateralis; tuberc. m. gastroc. med.¼tuberculum musculi
gastrocnemius, pars medialis. Scale bar¼1 cm.
FIGURE 4—1a, 1b, ventral and dorsal views, respectively, of left coracoid of
Caracara major n. sp. (MNHN 615). Gray parts in C. major n. sp. are
reconstructed assuming geometric scaling with Caracara plancus.
Abbreviations: ang. med. cor.¼angulus medialis coracoidei; facies artic.
sternalis.¼facies articularis sternalis; for. n. supracor.¼foramen nervi
supracoracoidei; impressio m. sternocorcoracoidei¼impressio musculi
sternocoracoidei; linea intermusc. vent.¼linea intermuscularis ventralis;
proc. lateralis¼processus lateralis coracoidei; proc. procor.¼processus
procoracoideus. Scale bar¼1 cm.
JONES ET AL.—A CARACARA FROM LATE PLEISTOCENE OF URUGUAY 153

(Baumel and Witmer, 1993; curved shape in Herpetotherinae; see
Jollie, 1976, fig. 155). The distance of the coracoidal foramen
from the procoracoidal rim is comparable to that observed in
Herpetotherinae genera (see Table 1; Fig. 6). However, the fossil
foramen has a more medial position in relation to coracoidal
shaft, a condition observed in all Caracarini species.
Scapula.—The corpus after the collum scapulae is missing. The
absence of a pneumatic foramen on the sulcus supracoracoideus
confirms the impossibility of the fossil belonging to the genera
Herpetotheres or Micrastur.
Sternum.—A fragment of left costal margin of sternum where
three intercostal spaces and their respective costal processes can
be observed.
Femur.—The epiphyses of the femur are missing. There is a
small, shallow nutrient foramen at the third distal portion of the
caudal side of shaft. Relative position and shape of the lateral and
medial tubercula of the muscle gastrocnemialis on the caudal side
are characters cited by several authors in phylogenetic studies of
avian groups (Livezey and Zusi, 2006 and references therein). In
C. major n. sp., these tubercula are very pronounced and have an
oval shape. Their shape resembles those of Caracarini species.
These tubercula are leveled at the proximal border of popliteal
fossa. Although intraspecific variation on the position of these
tubercula occurs, especially in Caracara species (i.e., see
Howard, 1938, figs. 6–9), in our extensive examination of extant
Caracarini species the particular condition on C. major femur
(Fig. 5) regarding this feature was never observed. On cranial
view, the intermuscular cranial line has the same orientation as in
Caracara species.
The mediolateral diameter of the femoral shaft of C. major is
larger relative to anteroposterior diameter, a condition observed
only in Thegornis musculosus Ameghino, 1895. In contrast, the
femoral shaft cross-section of the other falconids has a more
circular shape (Fig. 5).
Etymology.—From the Latin word major, meaning greater.
Holotype.—MNHN-615: a diaphysis of left femur, a left
incomplete coracoid, articular portion of right scapula, a fragment
of left costal margin of sternum, and shaft fragments of long
FIGURE 5—Distal portion of left femora of Caracarini species in posterior views (not to scale) and the corresponding cross-sections at mid-shaft. 1,Caracara
major n. sp. (MNHN 615); 2,Caracara plancus (MNHN 6254); 3,Caracara lutosus (USNM 19916); 4,Caracara prelutosus from late Pleistocene of United
States (NHMLAC 4587); 5,Caracara creightoni from Holocene of Cuba (WS 1933); 6,Caracara cheriway (USNM 553229); 7,Phalcoboenus australis (USNM
557987). Views 3–7 based on its depth and width measures and on C. plancus cross-section shape; gray parts in C. major n. sp. are reconstructed assuming
geometric scaling with Caracara plancus.
FIGURE 6—Ventral views of left coracoids of falconid species. 1,Caracara major n. sp. (MNHN 615); 2,Caracara plancus (MNHN 6254); 3,Caracara
cheriway (USNM 553229); 4,Ibycter americanus (USNM 621943); 5,Phalcoboenus australis (USNM 557987); 6,Herpetotheres cachinnans (MHNT 54); 7,
Micrastur semitorquatus (MHNT 1463); 8, scheme showing the measurements on the coracoid: segment b–a: coracoidal sterna end width (SW); segment a–d:
distance of angulus medialis to proximal rim of coracoidal foramen (DAMF); segment d–c: distance of proximal rim of coracoidal foramen to procoracoidal rim
at the base of procoracoidal processes (DFPR). Gray parts in C. major n. sp. are reconstructed assuming geometric scaling with Caracara plancus. Scale bar¼1
cm.
154 JOURNAL OF PALEONTOLOGY, V. 87, NO. 1, 2013

bones. The type material described here is housed in Museo
Nacional de Historia Natural, Montevideo, Uruguay. Measure-
ments on Tables 1 and 2.
Occurrence.—El Bagre Creek, at its mouth into the R´
ıodela
Plata estuary, San Luis town, Canelones Department, southern
Uruguay (S 34846017 00 ,W5583600700 ; see Fig. 1); late Pleistocene,
Libertad Formation (or Dolores Formation, see above).
DISCUSSION
Despite the fragmentary appearance of the material described
herein, the anatomical condition of the bones—regarding its
structures as well as the muscular lines, crests and impres-
sions—are strikingly well-preserved. The excellent preservation
allows comparison with almost all extant genera of Falconidae
in detail, offering a sufficient anatomical framework to erect a
new species within the genus Caracara.
Body mass estimations from the femoral cross-section
measurements yield an average body mass estimate of 3,700
(see Table 2). The estimation from the width of the coracoidal
sternal end could reflect a questionable result, due that the
dimension of this bone is severely constrained by the flying
capabilities (Feduccia, 1999). However, the proportions and
deep muscular impressions of the coracoid suggest a developed
flight condition for Caracara major n. sp., and for a regression
sample we chose only flying Falconiformes species (see
Appendix 2 data). The obtained result (3,767 grams) based on
width measure of coracoidal sternal end (SW of graphic
regression, see Appendix 2) falls within the estimated range
from all other body mass estimations (7,447 grams–1,550
grams; Table 2). The body mass estimation of Caracara
tellustris from the Holocene of Jamaica (Olson, 2008), obtained
here from tarsometatarsal diameter and length resulted in an
average of 3,815 grams (see Table 2). However, these
estimations should be considered as questionable. Certainly,
this species was a large caracara but its nearly flightless and
terrestrial condition previously suggested (Olson, 2008), could
have affected its tarsometatarsal dimensions. This tarsometarsus
is much enlarged and robust in comparison to the other
Caracara species, and the overall weak aspect of its incomplete
humerus and coracoid clearly reinforce the flightless hypothesis.
The coracoidal and humeral dimensions are strongly related to
the flight muscle mass (Feduccia, 1999). These muscles
represent approximately 20%of total body mass in flying birds
(Greenewalt, 1962; Rayner, 1988). The Caracarini species are
active fliers (Brown and Amadon, 1968; White et al., 1994) and
the supracoracoideus and pectoralis muscles have a considerable
relative mass. These features must be taken into account when
applying an allometric equation for flying birds (Alexander,
1983) in order to estimate the body mass. Therefore, it seems
that C. major would have been larger than the Jamaican species.
Although our results regarding C. tellustris body mass
estimations could be overestimated, it is likely that it would
have exceeded the body mass range of actual Caracarini species.
Body mass estimations of early Miocene species Thegornis
musculosus obtained from femoral and tarsometatarsal dimen-
sions have an average of 2,500 grams (see Table 2), a value far
smaller than these two Pleistocene species.
The maximum of body mass range of an extant falconid
corresponds to the female gyrfalcon (Falco rusticolus), with a
reported body mass of 2,000 grams (Brown and Amadon, 1968).
The new species described here almost doubles this mass (see
Table 2). Therefore, it is reasonable to consider C. major as an
unusually large falconid species, probably the largest known.
The great body size of C. major might have reinforced the
scavenging dominance that is observed in extant crested caracaras
TABLE 2—Measurements (in mm) of Caracara major n. sp. (MNHN 615), Caracara tellustris Olson, 2008 and Thegornis musculosus Ameghino, 1895. Body mass estimation (in grams) based on different methods
as noted below.
Species
Femoral midshaft
saggital diameter
Femoral midshaft
antero-posterior
diameter
Femoral minimum
mid-shaft circumference
estimation/body
mass estimation
from flying
bird sample
a
(range estimation)
Femoral shaft
least circumference
estimation/body
mass estimation
from general
avian sample–reduced
major axis
b
(range estimation)
Femoral shaft
least circumference
estimation/body
mass estimation
from bird of
prey sample–reduced
major axis
b
(range estimation)
Body mass
estimation from
femoral midshaft
sagittal diameter-flying
bird sample–Model I
c
(range estimation)
Tarsometatarsal
midshaft sagittal
diameter/body
mass estimation
from flying bird
sample–Model I
c
(range estimation)
Tarsometatarsal
length/body mass
estimation from of
flying bird
sample–Model I
c
(range estimation)
C. major n. sp. 11.24 9.87 34/3351
(4768–2355)
34/4240
(4518–3980)
34/3274
(7447–1550)
3862
(4639–3216)
——
C. tellustris — — — — — — 8.6
d
/4063
(7156–2307)
115.4
d
/3567
(4848–2624)
T. musculosus 10.8
e
7.54
e
29/2332
(3265–1665)
29/2055
(2627–1607)
29/2154
(4721–1055)
3512
(4218–2924)
— 95.04
e
/2015
(2739–1483)
a
Anderson et al. (1985)
b
Campbell and Marcus (1992)
c
Alexander (1983)
d
After Olson (2008)
e
After Noriega et al. (2011)
JONES ET AL.—A CARACARA FROM LATE PLEISTOCENE OF URUGUAY 155

with other avian scavengers (Wallace and Temple, 1987; White et
al., 1994). The living crested caracara is an accomplished avian
kleptoparasite; they have an opportunistic feeding behavior,
taking food from other raptors, marine and wader birds (White et
al., 1994; Fergusson-Lees and Christie, 2001). The increased size
of this new Caracara species might have resulted in the piracy of
a broad range of other birds, even in flight persecution. The
apparent well-developed flying capabilities and the greater body
size of C. major could have implied better gliding performance
and larger territory size than extant Caracarini species (Rayner,
1988; Palmqvist and Vizca´
ıno, 2003).
The large amount and size of megafaunal carrion that
probably would have existed during late Pleistocene environ-
ments could have favored the large body size of C. major.We
think that the significant size difference rules out a possible
clinal variety of living crested caracara (Caracara plancus)with
a reported maximum body mass of 1,600 in Chile and Peru
(White et al., 1994).
The great body size of C. major is comparable with large
buteonines and other accipitrids. Its significantly larger body
size could imply higher predatory skills when comparing with
living caracara species. The mean estimated body mass of C.
major exceeds, for example, that of the black-chested buzzard-
eagle (Geranoaetus melanolecus), which has a maximum
reported body mass of 3200 grams (report for a female
specimen, Ferguson-Lees and Christie, 2001). This living
speciesisfairlycommoninsouthernSouthAmericahabitats
and it is a large carnivorous bird that mainly predates mid-sized
mammals (Thiollay, 1994; Ferguson-Lees and Christie, 2001).
Based on the roughly similar body masses of both species, we
suggest that C. major probably could have predated on mid-
sized mammals that thrived during the late Pleistocene of
Uruguay (Ubilla, 2007). Due primarily to its great size, the
ecological role of C. major may have been distinct from any
extant caracara species.
ACKNOWLEDGMENTS
For the photographic material we are greatly indebted to B.
Schmidt and J. Dean, members of curatorial staff of Smithsonian
National Museum of Natural History. For the same reasons we
give thanks to S. Claramunt of American Museum of Natural
History, A. Farrell of Los Angeles County Natural History
Museum, W. Sua
´rez and Y.W. Garc´
ıa Lavin of Museo Nacional
de Historia Natural de Cuba. H. Alvarenga of Museu de Historia
Natural de Taubat´
eprovided access of comparative material
essential to this study. We are indebted to M. Pavia for his
valuable review and to E. Lindsay and S. Sensale for
improvement of English grammar. We also thank to Conselho
Nacional de Desenvolvimento Cient´
ıfico e Tecnol´
ogico, CNPq,
Brazil and CAPES Foundation, Ministry of Education of Brazil,
for doctoral research grants of RM (respectively processes
142462/2009–8 and BEX 9190/11–2), Agencia Nacional de
Investigaci´
on e Innovaci´
on (ANII) and Programa de Desarrollo de
Ciencias Ba
´sicas (PEDECIBA).
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ACCEPTED 27 JUNE 2012
APPENDIX 1
The coracoids, femora, and scapulae of the following specimens were used
for morphological comparisons, morphometrics, and body mass estimations.
Caracara plancus: MNHN 6254, 6390, 6391; Caracara cheriway:
USNM 553229, AMNH 11526, 13817, 27191; Caracara lutosus: USNM
19916; Caracara prelutosus: LACMHC H 4587, -E 651, -E 4236; Caracara
creightoni: WS 1933; Caracara tellustris USNM 535727; Thegornis
musculosus: MPM-PV-3443; Phalcoboenus australis: USNM 557987,
490979, AMNH 28200; Phalcoboenus megalopterus: USNM 500273,
AMNH 4960; Ibycter americanus: USNM 621943; Milvago chimachima:
MNHN 6264, MHNT 53; Milvago chimango: MNHN 5637, 5638; Micrastur
semitorquatus: MHNT 1125, 1463; Herpetotheres cachinnans: MHNT 54,
1959; Falco sparverius: MNHN 5639; Falco peregrinus: MHNT 1245;
Spiziapteryx circumcinctus: USNM 319444; Harpyhaliaetus coronatus:
MHNT 1815; Haliaeetus vocifer: MHNT 1935; Haliaeetus leucocephalus:
MHNT 520; Aquila chrysaetus: MHNT 514; Harpya harpyja: MHNT 1862,
4824; Necrosyrtes monachus: MHNT 49; Gyps fulvus: MHNT 917.
JONES ET AL.—A CARACARA FROM LATE PLEISTOCENE OF URUGUAY 157

APPENDIX 2—Data used in lineal regression for body mass (BM) estimation of Caracara major n. sp. (MNHN 615) from coracoid sternal end width (SW). Mean
body masses taken from Dunning (2007 and references therein). When sex of specimen is identified the correspondent mean body mass is considered.
Species Coracoid sternal end width (mm) Mean body mass (g)
Falconidae
Milvago chimachima MNHN 6264 /13.03 329
Milvago chimachima MHNT 53 11.29 299.5
Milvago chimango MNHN 5637 12.58 296
Milvago chimango MNHN 5638 11.67 296
Caracara plancus MNHN 6254 22.64 1,348
Caracara plancus MNHN 6390 24.94 1,348
Caracara plancus MNHN 6391 23.75 1,348
Caracara cheriway
1
USNM 553229 18.45 893.5
Herpetotheres cachinnans MHNT 54 17.06 672
Herpetotheres cachinnans MHNT 1959 17.29 672
Phalcoboenus australis USNM 490979/24.52 1,187
Phalcoboenus australis USNM 557987 22.68 1,187
Phalcoboenus australis AMNH 28200/23.7 1,187
Phalcoboenus megalopterus USNM 500273 18.86 788
Ibycter americanus USNM 621943 15.71 624
Micrastur semitorquatus MHNT 1463 16.92 739
M. semitorquatus MHNT 1125 19.09 739
Spiziapteryx circumcinctus USNM 319444?9.06 141
Falco sparverius MNHN 5639 7.59 115.5
Falco peregrines MHNT 1245 19.7 1,025
Accipitridae
Harpyhaliaetus coronatus MHNT 1815?31.5 2,950
Haliaeetus vocifer MHNT 1935/29 3,400
Haliaeetus leucocephalus MHNT 520 39.1 5,019
Aquila chrysaetos MHNT 514?35.8 3,900
Harpya harpyja MHNT 4824?37.5 4,800
Harpya harpyja MHNT 1862/41 8,300
Necrosyrtes monachus MHNT 49 27.5 2,043
Gyps fulvus MHNT 917 50.3 7,436
1
Specimen belongs to Southern population of C. cheriway (see Dunning, 2007).
Graphic of linear regression using reduced major axis (RMA) of coracoidal sternal end width (in mm) plotted against body mass (in grams). Regression
equation (error of regression coefficients) and Pearson’s r correlation have been calculated from 28 specimens of Falconiformes species (data above). Axes
expressed in decimal logarithms.
158 JOURNAL OF PALEONTOLOGY, V. 87, NO. 1, 2013