George E. McDaniel, Jr. & George T. Jefferson California Department of Parks and Recreation, Borrego Springs

Mammuthus meridionalis (Proboscidea: Elephantidae) from the Borrego Badlands of Anza-Borrego Desert State Park®, California: phylogenetic and biochronologic implications

McDaniel, G.E., Jr. & Jefferson, G.T., 2003 - Mammuthus meridionalis (Proboscidea: Elephantidae) from the Borrego Badlands of Anza-Borrego Desert State Park®, California: phylo- genetic and biochronologic implications - in: Reumer, J.W.F., De Vos, J. & Mol, D. (eds.) - ADVANCES IN MAMMOTH RESEARCH (Proceedings of the Second International Mammoth Conference, Rotterdam, May 16-20 1999) - DEINSEA 9: 239-252 [ISSN 0923-9308] Published 24 May 2003

A nearly complete skeleton of a mature female southern mammoth was recovered from the Borrego Badlands in Anza-Borrego Desert State Park®, California, USA. The remains represent a late evolutionary stage of the Mammuthus meridionalis (NESTI, 1825) chronocline, and constitute the most complete skeleton of this taxon in North America. Magnetostratigraphy and tephrochro- nology date the specimen at approximately 1.1 Ma BP. The osteology and osteometrics are pre- sented herein. This late stage of Mammuthus meridionalis co-existed with an early evolutionary stage of M. columbi (= M. imperator of some authors). Significant morphological differences between the two taxa from the Borrego Badlands suggest that M. armeniacus rather than M. meri- dionalis was immediately ancestral to M.columbi. A dispersal of M. armeniacus to North America approximately 1.2 Ma BP is implied. At least two mammoth lineages (excluding Mammuthus pri- migenius) are seen in North America. An early M. meridionalis lineage and a later M. armeniacus - M. columbi lineage. M. meridionalis is recognized as the earliest species of mammoth in North America.

Correspondence: California Department of Parks and Recreation, Colorado Desert District Stout Research Center, Anza-Borrego Desert State Park, 200 Palm Canyon Drive, Borrego Springs, California 92004, U.S.A; e-mail: [email protected]

Keywords: Mammuthus meridionalis, taphonomy, osteology, phylogeny

INTRODUCTION most complete skeleton of this taxon from In December of 1986, the skull, mandible and North America. about 70% of the skeleton of an adult female The site, ABDSP(IVCM) 1277, lies east of southern mammoth, Mammuthus meridionalis Borrego Springs and south of San Diego (NESTI, 1825) was discovered in the Borrego County road S22 (Fig. 1). Here, the fluvial- Badlands of northern Anza-Borrego Desert floodplain deposits of the Ocotillo Conglo- State Park® (ABDSP), California, USA by G. merate (Dibblee 1954, Remeika & Pettinga Miller of Imperial Valley College Museum 1991, Remeika 1992) have yielded a diverse (El Centro, California) (Miller et al. 1988; Irvingtonian North American Land Mammal Miller 1989; Parks et al. 1989; Miller et al. Age terrestrial vertebrate assemblage, describ- 1991; McDaniel & Jefferson 1997). The spe- ed as the Borrego local fauna by Remeika & cimen, ABDSP(IVCM) V5126, represents the Jefferson (1993), and Remeika et al. (1995).

239 ADVANCES IN MAMMOTH RESEARCH DEINSEA 9, 2003

Table 1 Dental measurements of ABDSP(IVCM) V5126. Explanation: TP = tooth position; L = length in mm; W = width in mm; CH = crown height in mm; PN = number of plates, + indicates minimum number, ( ) estimated number based on stage of wear; LF = lamellar frequency, number of plates / 10 cm, ( ) number of averaged measurements; ET = enamel thickness in mm, ( ) number of averaged measurements; M3/L = upper M3, left; M3/R = upper M3, right; M/3L = lower M3, left; M/3R = lower M3, right.

A thorough taphonomic study reveals that and gently curving with an Index of Curva- carnivores and scavengers prior to burial had ture significantly less than in M. imperator heavily damaged the carcass. Magneto- and M. columbi (Fig. 2). These characters stratigraphic and tephrochronologic methods distinguish M. meridionalis from the later date the specimen at approximately 1.1 Ma species (Agenbroad, pers. comm. 1996). The BP (Remeika & Beske-Diehl 1996). corpus of the mandible in ABDSP(IVCM) ABDSP(IVCM) V5126 represents a very V5126 is gracile rather than robust, and has a late evolutionary stage of Mammuthus meri- forward projecting mandibular symphyseal dionalis. The molar dental parameters fall process plus chin that is not turned down as well within the reported range of M. meridio- in M. imperator. The ascending ramus of nalis (see Maglio 1973) (Table 1). The skull ABDSP(IVCM) V5126 is low and inclined and mandible are shorter antero-posteriorly slightly posteriorly. In contrast, the ascending and wider than that in the imperial mammoth, ramus of M. imperator has rotated anteriorly. M. imperator (LEIDY, 1858). The incisor in Significant morphologic differences between ABDSP(IVCM) V5126 is thin, relatively long ABDSP(IVCM) V5126 and Mammuthus

Figure 1 Northern Anza-Borrego Desert State Park®, and the Borrego Badlands of eastern San Diego County, California. Explanation: SRC = Colorado Desert District Stout Research Center; S22 = county road 22; X = locality ABDSP(IVCM) 1277; dashed outlined area = Borrego Badlands.

240 MCDANIEL & JEFFERSON: Mammuthus meridionalis from Borrego Badlands

1 (N /2 of section 36, T10S R7E, Fonts Point 7.5 minute USGS topographic quadrangle) is transected on the southern side from south- west to northeast by the Valle Escondido anti- cline (Remeika, pers. comm. 1996). This structure plunges gently to the northeast, exhibits axial faulting, and has a very steeply dipping north limb which approaches vertical. The south limb steepens to over 300 near the axis of the anticline. Locality ABDSP(IVCM) 1277 lies south of the axis, where the strata strike approximately N260 E and dip gently 50 to 60 to the southeast. Stratigraphically, ABDSP(IVCM) V5126 was recovered from a predominately fluvial Figure 2 Scattergram of greatest length of incisor in cm / horizon that complexly interfingers with the Index of Curvature. Explanation: X = Mammuthus meridiona- lis ABDSP(IVCM) V5126; + = M. imperator ABDSP(IVCM) lacustrine Brawley Formation (Dibblee V4056; black dots = M. columbi (Agenbroad 1994); open cir- 1954). Individual beds pinch out to the east cles = M. primigenius (Haynes 1991; Kunz 1916). within the Brawley Formation (Remeika, pers. comm. 1996). The paleozoic metamor- imperator, as represented by ABDSP(IVCM) phic and mesozoic crystalline rocks in the V4214 and V4260, recovered from the same Santa Rosa Mountains to the north and north- stratigraphic horizon in the Ocotillo Conglo- west provide a source for the sandy fossilife- merate, make an ancestor-descendant rela- rous sediments that crop out on both limbs of tionship (Maglio 1973; Madden 1981) the Valle Escondido anticline. between these species highly unlikely. This implies that the steppe mammoth, M. arme- DEPOSITIONAL ENVIRONMENT niacus (FALCONER, 1857), rather than M. AND TAPHONOMY meridionalis, was immediately ancestral to Apparently, the skeleton was deposited within M. imperator. Mammuthus meridionalis is a 1m deep, ephemoral, braided stream chan- recognized as the earliest species of mam- nel system. The texture, sedimentary structu- moth in North America. As first suggested by res and bedding of these deposits are typical Harington (1984), it follows that M. meridio- nalis represents the end of one lineage, and M. imperator the beginning of a second lineage that arrived in North America approximately 1.2 Ma BP.

GEOLOGIC SETTING AND STRATIGRAPHY ABDSP(IVCM) V5126 was collected in a geologically complex area south of the east end of the seismically active San Jacinto Fault zone. This setting has made stratigrap- hic correlations with dated horizons within the Ocotillo Conglomerate difficult (Remeika & Beske-Diehl 1996). The general location Figure 3 Bone bed plan view, ABDSP(IVCM) 1277/V5126 (after Miller et al. 1991) (see element numbers,Table 2).

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Table 2 Represented skeletal elements of ABDSP(IVCM) V5126. Materials are listed by skeletal element number (see Fig. 3).

242 MCDANIEL & JEFFERSON: Mammuthus meridionalis from Borrego Badlands

of distal bajada, fluvial floodplain deposition- ments (Fig. 3, Table 2) indicate that the car- al environments. Local crossbedding and cass had largely decomposed and the remains channel direction at the excavation site sug- had been moved prior to burial. The scatter of gests a north/northeast to south/southwest skeletal elements, separation of once associa- current. Oxidization of iron-bearing minerals ted elements, the lack of many distal foot directly below most of the skeletal elements bones, and inferred depositional conditions, suggests that the fluvial channel may have suggests a short duration transport within the been dry for an extended period before depo- fluvial system after carcass decomposition. sition of the fossil-bearing layer. Also, some ABDSP(IVCM) 1277 was buried in fine- scouring or erosion occurred on the surface at grained siltstones, indicating low energy the time ABDSP(IVCM) V5126, was deposi- transport conditions that are consistent with ted. Overlying the specimen are distal fan Behrensmeyer's (1988) small scale, braided sheet flood deposits. stream channel-fill deposits. The lack of evi- There is no readily identifiable cause of dence of sediment abrasion (Olsen & Ship- death. Based on the extensive wear on the man 1988) on bone surfaces (Miller et al. anterior plates of the last molars (third 1991) is consistent with minimal fluvial molars), ABDSP(IVCM) V5126 was transport. The long axis orientation of the approximately 55 to 60 AEY (African ele- various skeletal elements within the main phant years) old (Haynes 1991) at the time of ABDSP(IVCM) V5126 bone cluster (Fig. 4) death. If AEY are applicable to Mammuthus indicates a northeast to southwest flow direc- meridionalis, the animal could have lived tion. This direction is consistent with that another 5 to 10 years. No skeletal evidence of determined from sedimentary structures. trauma and no spiral fractures indicating The skull rested in a nearly upright position green-bone breakage are present. The shallow with the left side slightly elevated out of the fluvial depositional environment rules out depositional plane. The orientation of the sediment entrapment or drowning. skull (anterior directed N15oE) and the main Osteopathologic evidence of long-term, bone concentration, with the long limb bones progressively debilitating arthroses is present located on the west side of the bone cluster in the degenerative state of the tempero-man- dibular articulations (see ‘Comparative Osteology and Osteometrics’ below). This condition would have made chewing increa- singly difficult and painful. The inability to feed adequately probably resulted in a weake- ned condition during life and may have con- tributed to starvation. Furthermore, predation is a distinct possibility with an infirm adult elephantid. Potential large predators in the Borrego local fauna include Borophagus diversidens (COPE 1893) (bone-eating dog), Arctodus simus (COPE 1879) (short-faced bear), and Homotherium sp. cf. H. serum (COPE 1893) (dirk-toothed cat) (Remeika and Jefferson 1993, Remeika et al. 1995). Undetectable short term, acute disease also Figure 4 Orientation of skeletal elements of ABDSP(IVCM) V5126. Explanation: large and small open circles = round or remains a possible cause of, or contribution nearly round large and small bones; line segments = long to death. bones, ends equal in size; line segments with dot = long bones The positions of the various skeletal ele- with one heavy end (dot).

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(Fig. 3), suggests that the animal died with its and the majority of the thoracic vertebrae are right side down and head directed upstream. missing. The anterior surfaces of the fifth and Given the inferred transport direction, the sixth cervical vertebrae were directed up, skull was transported less than the other ske- while that of the seventh was down. Two letal elements, and probably was moved very clusters of vertebrae, the fifth, sixth and little. The right incisor had become detached, seventh cervical vertebrae, and the third thor- and rotated 650 counter-clockwise (or less acic, second, third and fourth lumbar verte- likely, clockwise 2450) relative to the axis of brae lie to the east of, and are separated from the right alveolus. The tip of the incisor, the main concentration of skeletal elements which would have been more readily trans- (Fig. 3). Carnivores or scavengers moving ported relative to the larger/heavier proximal sections of articulated vertebral elements and end, came to rest under the right zygomatic individual bones away from the skeleton arch of the skull with the dorsal surface up. most easily explain this distribution. The left tusk remained rooted and accounts There is much evidence of gnawing on the for the skull being tipped to the right. The third lumbar vertebra. The position of the fact that the right incisor fell out and the left fourth lumbar vertebra and the two groups of incisor did not, may indicate that the peridon- vertebrae discussed above (Fig. 3), close to tal tissue of the right alveolus was damaged the southern slope of the exposed fossilife- when the animal presumably collapsed on its rous horizon, suggests that some of the mis- right side, allowing the incisor to become sing vertebral elements may have been lost more easily dislodged. through erosion. The mandible was transported approximate- Some ribs are complete, but many are mis- ly 5.8 m in the inferred flow direction away sing one or both extremities. Many ribs show from the skull. The symphysis pointed down- remnants of tooth marks and gnawing. A stream as expected. The position of the long number of ribs have tooth puncture marks on limb bones and the mandible indicate that the lateral edge, and pieces of the shaft of the these elements were among the first to beco- rib have been broken away. The ribs general- me disarticulated (Fig. 3). The mandible had ly are aligned at right angles to the direction to have been disarticulated prior to, or at of flow. The few rib that is aligned parallel to about the same time that the right incisor the flow direction retain a large/heavy proxi- became detached and moved. mal end. The distal ends of these ribs point Not all of the vertebrae of ABDSP(IVCM) downstream. A series of five grooves is pre- V5126 were recovered. Those remaining sent on the lateral and antero-lateral surfaces indicate that a great deal of postmortem pre- of the shaft of the left fourteenth rib in an depositional carnivore and/or scavenger acti- area 87.2 mm long and 48.7 mm wide. vity had occurred. Although only a few marks Detailed studies, including SEM imagery, typical of damage by carnivore canine teeth reveal that they are "U"-shaped in cross-sec- are evident, most vertebrae are missing part tion with no evidence of parallel striations. or all of most of the zygapophyses and pro- The deepest parts of four of these grooves are cesses as well as parts of the centra. These on the postero-lateral aspect of the rib, and are prime areas for gnawing by carnivores become shallower anteriorly. Very small frag- (Shipman 1981). The axis and third cervical ments of bone have been lost from the edges vertebra as well as the first and second thora- of the groove. The fifth mark is similar but cic vertebrae remained articulated. The ante- the direction is reversed. These features are rior surface of the first thoracic vertebra was typical of carnivore canine bite-and-glide oriented downward. These elements are posi- tooth marks. tioned with the dorsal spinous process poin- The left humerus and left ulna are aligned ting downstream. The fourth cervical vertebra with long axes parallel to the inferred flow.

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However, the long axis of the right humerus position of the front of the body (Fig. 3). The and that of the right tibia are oriented at near- sacrum was not found. ly 900 to the inferred transport direction (Fig. While some of the smaller skeletal ele- 3). These large elements should align parallel ments may have been lost through predation, to the flow direction. This suggests that more differential transport of many of the smaller, than one braid channel may have been invol- more equi-dimensional podials and foot ved in fluvial transport of the skeleton, or bones down stream and away from the main that the activities of scavengers affected their bone concentration, best explains their absen- orientation during the transport and burial ce in ABDSP(IVCM) V5126. Sorting of such processes. The innominates became separated elements from the larger/longer bones is con- from the sacrum and separated at the pubic sistent with low energy, fluvial transport con- symphysis. The left innominate was transpor- ditions (Behrensmeyer 1988). Some flaking ted about 3 m. The right, which is represen- of bone surfaces evidences stage two weathe- ted only by fragments, appears to have been ring (Shipman 1981). Most elements exhibit moved very little relative to the presumed some stage one weathering, indicating less

Table 3 Selected measurements, in cm, of the skull of ABDSP(IVCM) V5126. Measurement numbers correspond to those used by Agenbroad (1994). Explanation: L = left; M = midline or transverse; R = right.

245 ADVANCES IN MAMMOTH RESEARCH DEINSEA 9, 2003

Table 4 Asymmetry of the skull, ABDSP(IVCM) V5126.All measurements are in mm. * = The left malar bone is fractured and is displaced posteriorly.

than one-year exposure. Postburial damage to COMPARATIVE OSTEOLOGY AND the specimen resulted primarily from sedi- OSTEOMETRICS ment loading and compaction. Seasonal Wherever possible, the osteometrics proposed (average annual precipitation 16.5 cm) swel- by Agenbroad (1994), Olsen (1972), or ling and shrinking of clays within the matrix, Sisson and Grossman (1953), and the dental has fractured many elements. The skull exhi- terminology of Froelich & Kalb (1995) are bits minor vertical, top to bottom, crushing. used. A thorough osteometric study of all Most larger bones are fractured extensively skeletal elements has been completed both parallel and perpendicular to the long (McDaniel & Jefferson 1999). However, only axes (see Haynes 1983), and the ulna and those elements that show marked differences tibia exhibit depressed crushing on the up- between Mammuthus meridionalis and M. side of the diaphyses. Most of the recovered, imperator, the skull, mandible and scapula smaller elements are preserved intact. are discussed herein. Postburial groundwater leaching has altered extensively the bone chemistry but not the Skull morphology. Soil formation and plant growth Only the dorsal portion of the cranium is mis- have had little effect on the specimen. Recent sing. Although the remainder of the skull surface weathering and erosion at ABDSP exhibits some post-depositional crushing, it is (IVCM) 1277, prior to discovery of ABDSP essentially complete and intact. The right (IVCM) V5126, has resulted in considerable incisor is complete but separate. The root and damage to those elements exposed, including base of the left incisor are preserved in the most of the large limb bones. Total loss of alveolus. Both upper last molars (third some elements to surface weathering and ero- molars) are present and well preserved. sion is highly probable. Measurements of the skull are presented in Table 3. The skull, as a whole, is asymmetric, and exhibits congenital abnormalities. The ventral aspect of the mid-sagittal plane dis-

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plays a slight "S"-shaped curve. The left ABDSP(IVCM) V5126 are slightly divergent, upper molar and maxilla, and left basicrani- but not nearly as much as in M. imperator um are offset anteriorly 11 mm in the palatal and M. columbi (FALCONER, 1857) (see plane relative to the right side. This appears Gillette and Madsen 1993; Agenbroad 1994). to be largely developmental, although some The divergent angle at the base of the two displacement on post-depositional fractures incisors is 13o. The right medial alveolar mar- may contribute to this condition. The lateral gin diverges a few degrees to the right of the parts of the occipital bone are roughened for mid-sagittal plane, while the left veers nearly muscle attachments. Depressions for attach- 10o to the left of the mid-sagittal plane. The ment of the complexus tendons on the poste- posterior nares are partially divided by the rior surface of the occipital bone are 142.2 vomer bone, and together are slightly wider mm wide, 193.0 mm long, and 115.4 mm than long, measuring 106.6 mm by 94.8 mm deep. The foramen magnum is circular, and respectively. A supporting specimen cradle, measures 62 mm in diameter. prohibiting measurement covers the anterior Both occipital condyles are intact, and nares. The orbit is incomplete in the Elephan- show no fractures or erosion of the articular tidae, lacking the posterior part of the orbital surfaces. The two condyles are slightly ske- rim, and the supraorbital process of the frontal wed in the palatal plane. The left condyle is bone is shortened. The left orbital diameter placed about 2 cm anterior to the right. Post- (Table 4) in ABDSP(IVCM) V5126 is greater depositional distortion of the skull does not than the right. Post-depositional distortion of account for this asymmetry. The left condyle the skull does not account for the difference is larger than the right (Table 4). A matching between these dimensions. The zygomatic asymmetry is present in the prezygapophyses arches are asymmetric, largely a result of of the atlas, but not on the posterior articular post-depositional compressive fracturing. The surfaces. The articular surfaces of the tempor- greatest distance between the internal margin al condyles show considerable erosion, and of the left arch and the lateral surface of the osteopathology indicative of inflammation left maxilla is greater than that on the right and bone resorption. The surface of the left side (Table 3). The distance from the malar temporal condyle exhibits substantial pitting. bone to the temporal condyle is greater on the Pits average 5.4 mm in diameter and 0.8 mm right side than on the left (Table 3). However, in depth. The right temporal condyle displays the left arch is fractured immediately anterior much invivo deterioration. The articular sur- to the orbit, and the zygomatic process of the face is rough and irregular, and erosion of the left maxilla also has been fractured at the surface is extensive. A smooth, relatively flat, base of the premaxilla, and has been crushed secondary or false articular surface, measu- inward about 18 mm. ring 7.9 cm medio-laterally by 5.6 cm dorso- Important dimentional differences are pre- ventrally has developed on the anterior sur- sent between the skull measurements of face of the right postglenoid process. ABDSP(IVCM) V5126 (Table 3) and the Furthermore, the temporal condyles are une- sample (twenty three male individuals) of qual in size, the left being larger in all dimen- Mammuthus columbi from the Mammoth sions (Table 4). Site, Hot Springs, South Dakota (Agenbroad In the evolution of the skull of mammoths 1994). The premaxillae of ABDSP(IVCM) (Maglio 1973), the premaxillae rotate down- V5126 are longer, less divergent, and have a ward to an angle of 50-60o. In ABDSP(IVCM) greater diameter than in M. columbi. The V5126, the frontal-premaxilla plane is flat, upper molars (third molars ) are farther apart. while in Mammuthus imperator as represen- The skull of ABDSP(IVCM) V5126 is wider ted by ABDSP(IVCM) V4260, the premaxil- transversely but not as long antero-posteriorly lae have rotated ventrally. The premaxillae of as the Hot Springs specimens.

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Table 5 Selected measurements, in cm, of mandibles of Mammuthus meridionalis ABDSP(IVCM) V5126 and of M. imperator ABDSP(IVCM) V4260. Measurement numbers correspond to those used by Agenbroad (1994). * = condyles missing.

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Table 6 Comparison of the characteristics of Mammuthus meridionalis (ABDSP [IVCM] V5126), M. armeniacus, and M. imperator, ABDSP(IVCM) V4260.

ABDSP(IVCM) V5126 exhibits the same inclined posteriorly than in Mammuthus differences with respect to specimen USHS imperator and M. columbi, in which the rami 88.18.52 from Huntington, Utah, identified as have rotated anteriorly and are vertical to the a large male M. columbi (Gillette & Madsen corpus. The coronoid processes in later spe- 1993). The Huntington specimen is geologi- cies are anterior to the posterior margin of the cally older and larger in size than those from lower molars. Consequently, the height of the Hot Springs. ascending ramus is greater in both ABDSP (IVCM) 4260 (Table 5) and Hot Springs Mandible sample (Agenbroad 1994) than in ABDSP With the exception of both condyles, the (IVCM) V5126. mandible in ABDSP(IVCM) V5126 is com- plete and symmetric. The corpus of the denta- Dentition ry is relatively gracile compared to the robust Both the upper and lower last molars (third dentary in ABDSP(IVCM) V4260 (Table 5). molars of Saunders 1970, Madden 1981, and The anterior symphyseal process of the man- Froelich & Kalb 1995; the sixth molars of dible of ABDSP(IVCM) V5126 is longer, and Laws 1966) of ABDSP(IVCM) V5126 are extends forward rather than downward as in preserved intact. The teeth are in full wear, latter specimen. The mandibles of Mammu- with the first two or possibly three plates thus imperator and M. columbi are morpholo- worn away. The dental parameters (Maglio gically more similar to each other than to this 1973) of ABDSP(IVCM) V5126 fall within element in M. meridionalis. As with the skull, the range of Mammuthus meridionalis (Table the mandible of ABDSP(IVCM) V5126 is 1). The asymmetry of the skull is seen in the shorter antero-posteriorly and wider than that maxillary placement of the upper molars. in ABDSP(IVCM) V4260 (Table 5) and the Both the upper and lower molars on the right Hot Springs Mammoth Site sample (Agen- side are worn considerably more than those broad 1994). The corpora of both ABDSP on the left. This indicates that the animal (IVCM) V4260 and in the Hot Springs sample chewed much more frequently or heavily on are much higher dorso-ventrally and wider the right side. Such behavioral asymmetry transversely (more robust) than that of may be habitual in healthy individuals. ABDSP(IVCM) V5126. The ascending rami However, it is likely that asymmetric chew- of ABDSP(IVCM) V5126 are much more ing in ABDSP(IVCM) V5126 was due to pain

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Figure 5 Suggested phylogeny and chronology of Mammuthus in North America.

associated with the pathologic tempero-man- of the tip of the incisor of ABDSP(IVCM) dibular joint. The right incisor of ABDS V5126, and a larger wear facet on the distal (IVCM) V5126 is fully intact. From the 150.8 mm of the lateral surface. Thus, the tip alveolus, it extends downward, gently curving of the tooth is not conical, but flattened on laterally, then upward, and finally curving both the lateral and medial surfaces. The medially. This long sweeping, gentle "S"-sha- incisor pulp cavity in female elephantids fills ped compound curve has a low ‘Index of in after maturity, while that in males remains Curvature’ (Table 6) in contrast to the sharply open (Haynes 1991). A very shallow pulp curved incisors of Mammuthus imperator and cavity is present in the right incisor of M. columbi (Fig. 2) (Agenbroad, pers. comm. ABDSP(IVCM) V5126. This character and 1996). The incisor of ABDSP (IVCM) V5126 the basal diameter of the incisor indicate the is thinner, longer, and much less curved than specimen is female. those in the Hot Springs sample (Agenbroad 1994). All of these are much shorter than CONCLUSIONS ABDSP(IVCM) V5126, the longest being Major differences in the morphology of the 277 cm maximum length, and 177 cm cord skull, mandible, incisor, and cheek teeth of length. Only four Hot Springs specimens specimens of Mammuthus meridionalis and have an Index of Curvature less than M. imperator (Table 6), recovered from the ABDSP(IVCM) V5126, and these are less same stratigraphic horizon, argue against an than 150 cm maximum length (Fig. 2). Of the ancestor-descendant relationship between twenty two specimens measured by these species as previously thought (Maglio Agenbroad (1994), only six have a basal dia- 1973; Madden 1981). Mammuthus meridiona- meter less than that of ABDSP(IVCM) lis is recognized as the earliest species of V5126 (17.2 cm). There is a small wear facet mammoth in North America. The taxon repre- on the distal 66.2 mm of the medial surface sents the end of a lineage that persisted here

250 MCDANIEL & JEFFERSON: Mammuthus meridionalis from Borrego Badlands

from about 1.8 to 1 Ma BP. M. imperator Loxodonta africana - East African Wildlife Journal 4: represents the beginning of a second, M. 1-37 imperator - M. columbi lineage that co-exis- Madden, C.T., 1981 - Mammoths of North America - ted with the former in North America from Doctoral Dissertation, Department of Anthropology, approximately 1.2 to 1 Ma BP (Fig. 5). University of Colorado, Boulder At least three separate dispersals of Mammu- Maglio, V.J., 1973 - Origin and Evolution of the thus from Eurasia to North America have Elephantidae - Transactions of the American occured, the earliest at approximately 1.8 Ma Philosophical Society, New Series 63: 1-149 BP with appearance of M. meridionalis, the McDaniel, G.E., Jr. & Jefferson, G.T., 1997 - A nearly second at 1.2 Ma BP with the appearance of complete skeleton of Mammuthus meridionalis from M. armeniacus/M. imperator (Harington the Borrego Badlands, Anza-Borrego Desert State 1984), and the third in the late Pleistocene Park, California - in: Mojave Desert Quaternary with the arrival of the wooly mammoth, M. Research Symposium, Abstracts of Proceedings - San primigenius (BLUMENBACH, 1803) (Fig. 5). Bernardino County Museum Association Quarterly 44 (1): 29-30 REFERENCES McDaniel, G.E., Jr. & Jefferson, G.T., 1999 - Agenbroad, L.D., 1994 - Taxonomy of North American Mammuthus meridionalis from the Borrego Badlands, Mammuthus and biometrics of the Hot Springs Anza-Borrego Desert State Park®, Borrego Springs, Mammoth Site of South Dakota - in: Agenbroad, L., California - Manuscript on File, Colorado Desert & Mead, J.I., (eds.) - pp. 158-207, Hot Springs, District Stout Research Center, Borrego Springs, South Dakota California Behrensmeyer, A.K., 1988 - Vertebrate preservation in Miller, G.J., 1989 - A preliminary report on a half-a-mil- fluvial channels - Paleogeography, Paleoclimatology, lion year old cutmarks on mammoth bones from the Paleoecology 63: 183-199 Anza-Borrego Desert Irvingtonian - in: Symposium Dibblee, T.W., Jr., 1954 - Geology of the Imperial Valley on the Value of the Desert - p. 8, Anza-Borrego region, California - CaliforniaDivision of Mines Desert Foundation, Borrego Springs, California, Bulletin 170 (2): 21-28 Abstracts Froelich, D.J. & Kalb, J.E., 1995 - Internal reconstruction Miller, G.J., Remeika P., Parks, J.D., Stout, B. & Waters, of elephantid molars: applications for functional V.E., 1988 - A preliminary report on a half-a-million anatomy and systematics - Paleobiology 21 (3): 379- year old cutmarks on mammoth bones from the 392 Anza-Borrego Desert Irvingtonian - in: Mojave Gillette, D.D. & Madsen, D.B., 1993 - The columbian Desert Quaternary Research Symposium, Abstracts of mammoth, Mammuthus columbi, from the Wasatch Proceedings - San Bernardino County Museum Mountains of central Utah - Journal Paleontology 67 Association Quarterly 35 (3-4): 41 (4): 669-680 Miller, G.J., Remeika P., Parks, J.D., Stout, B. & Waters, Harington, 1984 - Mammoths, bison, and time in North V.E., 1991 - A preliminary report on a half-a-million America - in: Mahaney, W.C. (ed.) - pp. 299-309, year old cut marks on mammoth bones from the Quaternary Dating Methods, Elsevier Science Anza-Borrego Desert Irvingtonian - Imperial Valley Publishers B.V., Amsterdam College Museum Society Occasional Paper 8: 1-47 Haynes, G., 1983 - Frequencies of spiral and green bone Olsen, S.J., 1972 - Osteology for the Archeologist, no. 3, fractures on ungulate limb bones in modern surface the American Mastodon and the Woolly Mammoth - assemblages - American Antiquity 48 (1): 102-114 Peabody Museum, Cambridge, Massachusetts Haynes, G., 1991 - Mammoths, mastodons, and Olsen, S.L. & Shipman, P., 1988 - Surface modification elephants - Cambridge University Press, England on bone: trampling versus butchery - Journal of Kunz, G.F., 1916 - Ivory and the elephant in art - in: Archeological Science 15: 535-553 Archeology and Science - Garden City, N. Y. Parks, J., Stout, B., P. Remeika, P. & Waters, V., 1989 - Doubleday, Page and Co. A progress report on half-million-year old marks on Laws, R.M., 1966 - Age criteria for the African elephant, mammoth bones from the Anza-Borrego Desert

251 ADVANCES IN MAMMOTH RESEARCH DEINSEA 9, 2003

Irvingtonian - in: Mojave Desert Quaternary Research tology of the western Borrego Badlands, Anza- Symposium, Abstracts of Proceedings - San Borrego Desert State Park, California - in: Reynolds, Bernardino County Museum Association Quarterly 36 R.E. & Reynolds, J. (eds.) - Ashes, Faults and Basins (2): 63 - 93 (1): 90-93, San Bernardino County Museum Remeika, P., 1992 - Preliminary report on the stratigra Association Special Publication MDQRC phy and vertebrate fauna of the middle Pleistocene Remeika, P., Jefferson, G.T. & Murray, L.K., 1995 - Ocotillo formation, Borrego Badlands, Anza-Borrego Fossil vertebrate faunal list for the Vallecito-Fish Desert State Park, California - in: Mojave Desert Creek and Borrego-San Felipe Basins, Anza-Borrego Quaternary Research symposium, Abstracts of Desert State Park and vicinity, California - in: Proceedings - San Bernardino County Museum Remeika, P. & Sturz, A. (eds.) - Paleontology and Association Quarterly 39 (2): 25-26 Geology of the Western Salton Trough Detachment, Remeika, P., 1995 - The Borrego local fauna: revised Anza-Borrego Desert State Park, California - 1: 82- basin-margin stratigraphy and paleontology of the 93, San Diego Association of Geologists, Field Trip western Borrego Badlands, Anza-Borrego Desert Guidebook State Park, California - Revised from the San Remeika, P. & Pettinga, J.R., 1991 - Stratigraphic revi Bernardino County Museum Association Special sion and depositional environments of the middle to Publication MDQRC, 93(1):90-93 - in: Remeika, P., late Pleistocene Ocotillo Conglomerate, Borrego & Sturz, A. (eds.) -Paleontology and Geology of the Badlands, Anza-Borrego Desert State Park, California Western Salton Trough Detachment, Anza-Borrego - Symposium on the Value of the Desert - p. 13, Desert State Park, California - 1: 97-103, San Diego Abstracts, Anza-Borrego Desert Foundation, Borrego Association of Geologists, Field Trip Guidebook Springs, California Remeika, P. & Beske-Diehl, S., 1996 - Magneto- Saunders, J.J., 1970 - The distribution and taxonomy of stratigraphy of the Western Borrego Badlands, Anza- Mammuthus in Arizona - Master of Science Thesis, Borrego Desert State Park, California: implications Department of Geochronology, University of Arizona for stratigraphic age control - in: Abbott, P.L. & Shipman, P., 1981 - Life History of a Fossil - Harvard Seymour, D.C., (eds.) - Sturzstroms, and Detachment University Press, Cambridge, Massachusetts Faults, Anza-Borrego Desert State Park, California - Sisson, P. & Grossman, J.D., 1953 - The Anatomy of pp. 209-220, South Coast Geological Society, Field Domestic Animals - Fourth Edition, Revised, W.B. Trip Guidebook Saunders Company, Philadelphia, Pennsylvania Remeika, P. & Jefferson, G.T., 1993 - The Borrego local fauna: revised basin-margin stratigraphy and paleon received 20 May 1999

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