Orycteropus undetermined

Lehmann, Thomas, 2009, Phylogeny and systematics of the Orycteropodidae (Mammalia, Tubulidentata), Zoological Journal of the Linnean Society 155 (3), pp. 649-702 : 689-690

SPECIES ORYCTEROPUS SP. SWARTKRANS

Material: Several isolated phalanges of the foot ( SKX 75 ; SKX 498 ; SKX 1199 ; SKX 37832), housed at the Transvaal Museum, Pretoria. Lehmann (2004) identified these specimens as Orycteropus sp .

Locality and age: Swartkrans, Member 2 and Member 3 ( South Africa). Member 2 is dated to around 1.5 Mya, and Member 3 is at least 1-Myr old ( Brain, 1993).

Discussion: The very fragmentary aardvark material from Members 2 and 3 can only be compared by size with other Tubulidentata . Indeed, these phalanges are similar to their counterparts in O. afer in their morphology. The dimensions are also comparable with those in O. afer , but the phalanges are more slender. Therefore, I consider that these specimens belong to the genus Orycteropus , but are too fragmentary to enable a specific identification.

INCERTAE SEDIS

SPECIES ORYCTEROPODINAE SP. CHINJI

Material: Fragment of left hemimandible with P 3 –M 2 ( AMNH 101259 ), housed at the AMNH, New York; fragment of hemimandible with P 3 –M 1 ( GSI K13 /448), probably housed at the Geological Survey India, Calcutta; proximal and intermediate phalanges of the hand ( GSP 4346 ) and a terminal phalanx ( GSP 767 ), probably housed at the Geological Survey Pakistan, Islamabad; and elements of a post-cranial skeleton ( GSP S 234 ), housed at the Harvard Peabody Museum, Cambridge, USA. Pickford (1978) reported these specimens as ‘ Orycteropus sp. indet. small’ .

Remarks: The specimens GSP 767, GSP 4346, and GSI K13/448 have not been directly seen by the author.

Locality and age: Dhok Talian, Chinji, and Chinji Bungalow in the Potwar Plateau, as well as Sind ( Pakistan). The Potwar Plateau specimens come from the Middle Miocene Chinji Formation, dated to between 14.2 and 11.2 Mya ( Barry et al., 2002). The Sind material also comes from the Chinji Formation, according to Pickford (1978).

Discussion: In his revision of the fossil aardvark from Pakistan, Pickford (1978) reported the presence in the Siwaliks of another species (undetermined), smaller than A. browni , but too fragmentary to warrant the erection of a new name yet. From the available material, one can observe that the lower molars are rectangular and present subequal lingual and vestibular grooves, as in Orycteropus and Myorycteropus species , as well as in aff. A. pottieri . However, the dimensions of these teeth are significantly shorter than in any of the known species of Orycteropus . Indeed, the teeth are intermediate in size between those of M. africanus and aff. M. minutus , on the one hand, and Amphiorycteropus , on the other hand. The teeth are also very slender, as in M. africanus , and are almost as slender as those in aff. M. chemeldoi . The postcranial elements are also very small. The acetabular fragment of GSP S 234, for instance, is equivalent in size to that of aff. M. minutus and Leptorycteropus . The fragment of metacarpal (GSP S 234) is close in size to aff. M. chemeldoi and A. abundulafus . The calcaneum (GSP S 234) is slightly smaller than in M. africanus . Conversely, the metatarsals and the intermediate phalanges of the foot show a larger size than in the Kenyan taxon, and are closer to A. abundulafus . The contradictory results obtained by the biometrical analysis hinder an accurate identification. There are no discrete characters to really point towards a particular species, or even to a genus. Until further material is discovered, I therefore suggest placing these specimens in generic and species indetermination.

SPECIES ORYCTEROPODINAE SP. FORT TERNAN

Material: Two phalanges of the foot ( KNM FT 3326 ; KNM FT 3327 ) described by Pickford (1975) as part of the hypodigm of ‘ Orycteropus chemeldoi ’. The specimens are housed at the NMK, Nairobi .

Remarks: These specimens were identified as phalanges of the hand by Pickford (1975).

Locality and age: Fort Ternan, level IV ( Kenya), dated to around 14 Mya (see Hill et al., 2002).

Discussion: The type series of aff. M. chemeldoi has been found in the Tugen Hills. Nonetheless, Pickford (1975) added these two specimens from Fort Ternan to the hypodigm of his new species. Even with their misidentification as medial and proximal phalanges of the hand, there is no comparable counterpart for the Fort Ternan specimens in the material of aff. M. chemeldoi from the Tugen Hills. Therefore, I withdraw this material from the hypodigm. Moreover, this material is too fragmentary to allow any precise identification at the genus and species level: more material is needed.

SPECIES ORYCTEROPODINAE SP. KAKARA

Material (the specimen has not been directly seen by the author): Isolated proximal phalanx of the foot ( KI 79 ′92), previously attributed to ‘ O. cf. chemeldoi ’ ( Pickford, 1994). The specimen might be housed at the Uganda Museum , Kampala .

Locality and age: Specimens found at locality KI6 from the Kakara Formation ( Uganda), dated to around 10 Mya ( Pickford, 1994).

Discussion: Typical orycteropodid proximal phalanx, with dimensions only matching those of the second proximal phalanx of the holotype of M. africanus (no homologous element is known for aff. M. minutus and aff. M. chemeldoi ). However, the material is too fragmentary to give an accurate determination, and is thus placed in generic and specific indetermination.

SPECIES ORYCTEROPODINAE SP. KORU

Material: a left M 1 (?) ( M 14265 ), housed at the NHM, London; a fragment of mandible with M 2 and an isolated M 3 (KNM-KO-84), housed at the NMK, Nairobi.

Remarks: The specimen M 14265 has not been directly seen by the author.

Locality and age: Koru (GPS: 0°10′S, 35°15′E, according to MacInnes 1956) and locality 31 (Koiyabi) ( Kenya) from the Koru Formation. The Koru Formation is dated to between 19.6 and 19.5 Mya ( Pickford & Andrews, 1981).

Discussion: Pickford & Andrews (1981) reported one aardvark specimen found at Koru between 1977 and 1979. They considered it to be ‘ Orycteropus minutus ’ in their faunal list, but gave no description. This specimen, a left hemimandible fragment (KNM KO 84) is of small size, but is larger than the mandibles of any of the Myorycteropus species. The lower molars show a trapezoidal outline, and a lingual groove slightly shallower than the vestibular one. This configuration is different from the lower molars of M. africanus , but can be compared with that in aff. M. minutus , the species from the genus Amphiorycteropus , and, more particularly, with aff. A. seni . However, the dimensions of the teeth are larger than in aff. M. minutus , and are close to those of Amphiorycteropus taxa.

The size of this isolated left M 1 (?) ( M 14265 ), described by MacInnes (1956) as ‘ Orycteropus sp. indet’, is not incompatible with the size of KNM KO 84. Therefore, I associate the two specimens in this description. The dimensions of the upper molar are again closer to those in Amphiorycteropus and the smallest Orycteropus specimens than to Myorycteropus . No description of the lingual groove and of the outline of the tooth are given, but based on its size, MacInnes (1956: 27) was confident that this specimen ‘is certainly not another example of Myorycteropus ’. The material found at Koru is too fragmentary to give an accurate identification. Thus, I recommend keeping these specimens in species and genus indetermination until more material is found. The specimens from Koru potentially represent one of the oldest remains of fossil Tubulidentata ascertained so far. Nonetheless, it is possible that these specimens were found in pockets of younger sediments (M. Pickford, pers. comm.), which would explain their relatively large size.

SPECIES ORYCTEROPODINAE SP. PROCHOMA

Material (the specimens have not been directly seen by the author): Two phalanges ( PXM 259 ; PXM 260 ) described by de Bonis et al. (1994) as ‘ Orycteropus sp .’.

Locality and age: Prochoma 1 ( Macedonia, Greece), dated from the Late Miocene (MN11).

Discussion: As stated by de Bonis et al. (1994: 356): ‘these remains are too fragmentary for a specific identification’. Therefore, and in regard to the delicate generic determination of specimens geographically and chronologically close to these specimens, I recommend keeping this aardvark material from Prochoma in generic and specific indetermination, until new material is discovered.