Mammut obliquelophus Blumenbach 1799
Creators: name: Yaghoubi, Sadaf
name: Ashouri, Ali Reza
name: Ataabadi, Majid Mirzaie
name: Ghaderi, Abbas
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Proboscidea
Mammutidae
Mammut

description: “ Mammut ” cf. obliquelophus (Mucha, 1980).
Synonyms: Mammut praetypicum Kubiak, 1972
Mastodon americanus Kerr, 1792; Hopwood, 1935, pp. 43–46, Pl. 6.5
Mammut borsoni (Hays, 1834): Tobien et al., 1988, p. 165–168, Figs. 57, 58 (see Wang et.al. 2017).
Stratigraphic occurrence: Turolian; MN 11(Koufos, 2013) to MN 13 (Van Dam et al., 2001).
Geographic distribution: China (Baode Region), Southern Russia, Ukraine, Slovenia, North Macedonia, Moldova, Greece, Bulgaria, Hungary, Spain, Turkey.
Referred materials: Right M 3 (MMTT11 [PRCI/V001]) and a pair of adult upper tusks (MMTT1 a, b) from Abkhareh (Varzeghan), Iran.
Description
The right M 3
The specimen preserves three roots, and molar crown is adequately preserved in exhibiting zygodont characters. The tooth has three major lophs plus a reduced 4th loph at the posterior end. A median sulcus separates the pretrite and posttrite lophs.
The anterior cingulum is moderately developed. The protocone (abaxial pretrite conelet of the first loph) is strongly worn down and is connected to the anterior cingulum. The paracone (main posttrite conelet of the first loph) is slightly worn, and the number of mesoconelets seems to be two or three. Hypocone and metacone are worn to some extent, with one and two mesoconelets, respectively. Crescentoids are weak on the first and second pretrite lophs, but the third pretrite loph bears crescentoids on its anterior wall. The posttrite lophs possess zygodont crests on the posterior wall of the first posttrite cusp and on the anterior wall of the second posttrite cusp, which are hardly developed. The pretrite lateral enamel is well-developed. The pretrite third half loph consists of a cone and one mesoconelet, which are almost worn and carry crescentoids on their anterior slope. The posttrite third loph is worn so that the number of mesoconelets is unclear. The fourth loph is strong but shorter than the first three and consists of two pretrite and posttrite conelets. The posterior cingulum is moderately weak. The transverse valleys are completely open and broad (Figs. 2, 3, 4). The measurements of the third upper molar teeth is available in Table 1.
The cranium Kubiak (1972) described has two upper molar teeth: M 2 and M 3. The M 2 is trilophodont, complete, but deeply worn down. The third molar is broken, and only 1st and 2nd lophs are preserved. The anterior lophs are relatively worn. There are no conules between ridges in Kubiak’s M 3 material, and half lophs are almost symmetrical in width but not in morphology. It seems that the first pretrite loph and the first posttrite loph consist of two or three mesoconelets, which are relatively worn. However, the morphology of the first and the second lophs of M 3 from Balta Sands (Podolia, Ukraine, Kubiak, 1972, pl. XII, Fig. 7) are almost similar to the Abkhareh M 3. So, the assignments of Abkhareh tooth to “ Mammut ” cf. “ M. ” obliquelophus can be based on its zygodont morphology and its similarity to the Kubiak material.
Upper tusks
A pair of I 2 (MMTT 1 a, b) was found in Abkhareh village near the Varzeghan area proximate to the zygodont molar tooth (previously described in the current study). They were prepared especially in their proximal part and were covered by protective material. The left tusk is broken into two parts, but the right one is almost complete and preserved well. In situ, and in lateral view, the upper tusk is curved dorsally and seems to be directed straight or slightly downwards and then bends strongly outwards after the secondary medial of its length. So, the tip is turned upwards. Tusks are not helicoidal, without torsion, and diverged in anterodorsal view. The tusks are characterized by a polished surface on their distal ends on the medial sides of both of them. Distal tips are almost abraded, forming a partly distinct elliptical shape on each tusk. Dorsal and ventral wear facets are absent (Fig. 5a). No enamel band was recognized. There is a clear longitudinal furrow on their lateral (labial) side. Unfortunately, the pulpa of both the right and left tusks was covered with some glue during the reconstruction. So, it is not possible to see the pulpa.
The maximum lengths of MMTT1a and b (taken dorsally tangentially from the proximal end to the distal end (tip) of the tusk) are 1310 mm and 1360 mm, and their lengths are 1080 mm and 1000 mm, respectively. The maximum diameter of MMTT1a (taken at the middle of the tusk) is 480 mm, and that of MMTT1b is 440 mm (Figs. 5, 6).
No sign of crossing Schreger lines was seen on the ivory’s cross-section and broken surfaces. Still, their absence cannot be interpreted as definite since we could not observe the fresh sectional surface of the tusk ivory. Although the best trait to distinguish Elephantimorpha from more basal proboscideans, such as deinotheres, is the presence of Schreger lines, we relied on the tusk morphology. So, Abkhareh materials’ assignment to the genus Mammut sp. is based on their slight curvature and untwisted morphology and absence of enamel band.
According to Jafarzadeh and Konidaris (2020), Neogene elephantimorphs from Eurasia generally have straight or less curved and untwisted upper tusks (except Choerolophodon), this is particularly true about mammutids from the Miocene, including Zygolophodon and Mammut.
The few scattered fossil bones were found on the surface sediments in Abkhareh. The close spatial accumulation of the tusks with the isolated tooth from Abkhareh may indicate that those do indeed belong to a single mammutid individual. This may also be the case with the deinothere postcranial materials and maxilla with some teeth, which were attributed to an adult individual of Deinotherium gigantissimum due to their immediate proximity and consistent size (Pickford & Pourabrishami, 2013; Pourabrishami, 2004).
Therefore, it is supposed that this fossiliferous layer on the surface was a burial ground for several contemporary taxa that were washed away by seasonal rivers and buried individually.
Comparison
There are not many reports of “ Mammut ” obliquelophus. However, Markov (2008) argued that “ Mammut praetypicum ” (if it is taxonomically valid name) might be a senior synonym of “ M.” obliquelophus presented by Kubiak (1972).
Among the Balta Sands materials in Podolia, Ukraine (Kubiak, 1972, p. 311), there is a partial skull with associated dextral I 2. The tusk is relatively large (1000 mm long) and almost straight. According to his notes, the tusk projects a cranium along an almost horizontally forward trajectory. However, “it is directed slightly downwards and markedly outwards and slightly turned upwards at the end”. Abkhareh tusks MMTT1a, b seem to be directed almost downward, and do not leave the skull horizontally. They are outwards and exhibit upward turns at their tips and much stronger dorsal up-curve. The cross-section in Kubiak’s I 2 is circular, and MMTT1 of Abkhareh shows a circular cross-section at its proximal pulp. It is almost circular in the middle of the tusk. Some “regular longitudinal streaks in the outer and inner layers of the dentine” were observed by Kubiak (1972, p. 311, PL. XIII: F.9). However, the same feature on Abkhareh tusks is not noticeable.
Another notable upper tusk specimen from a Late Miocene Eurasian mammutid is a Turolian right tusk numbered NKP-1 from Neokaisareia in Pieria, Northern Greece, referred to as “ Mammut ” obliquelophus (Konidaris & Tsoukala, 2020). Its maximum length is 930 mm, and its maximum diameter is 87.3 mm, slightly shorter and slender than Abkhareh tusks (1080 mm in length).
NKP-1 tusk is almost straight with slight upward (dorsal) curvature in lateral view. It is twisted and slender (according to the author, the NKP-1 tusks belong to an ontogenetically young and/or female, which can explain why its diameter is less than the diameter of the Abkhareh one). Several longitudinal furrows run along the tusk of NKP-1, and the enamel band is absent (Konidaris & Tsoukala, 2020). Both the Balta Sands (Kubiak, 1972; Markov, 2008) and the Neokaisaria (NKP-1) right upper tusks (Konidaris & Tsoukala, 2020) have similarities in some degrees with Abkhareh tusks. All are almost straight with slight dorsal curvature in lateral view.
As mentioned, only a few I 2 materials are called Mammut obliquelophus. The material from the Hualinsanhe locality in Gasu Province, Northwest China (almost complete cranium), belongs to a juvenile individual Wang et al. (2017). It has a pair of in situ upper tusks. The tusks are short and slender. The cross-section is round. As expected in juveniles, the apical part is covered by enamel. The skull from Hualinsanshe was attributed to Mammut cf. M. obliquelophus by Wang et al. (2017). Although some characteristics of the tusks from Hualinsanhe, like bending ventrally in lateral view, lacking enamel band on the lateral side and slight torsion, being divergent in anterior view, and becoming slender apically are almost similar to Abkhareh ones, it does not seem feasible to compare such a specimen belonging to a very young individual with the tusk of Abkhareh belonging to a completely grown adult individual.
“ Mammut ” borsoni (Hays, 1834) is the classic Pliocene–earliest Pleistocene mammutid recorded wide across Northern Eurasia (Tobien, 1996), yet it has never been reported from Iran. Besides, it is likely that “ M. ” borsoni has longer upper tusks than “ M. ” obliquelophus. However, the symphysis is longer than the tooth row, and lower tusks are well-developed in “ M. ” obliquelophus. As in a specimen of “ M.” borsoni reported from Milia in Grevena, Greece (Tsoukala, 2000; Tsoukala & Mol, 2016), the length of its upper tusks reaches 4.39 m. The upper tusks of “ M. ” borsoni are approximately straight and slightly up-curved (dorsally), slender, torsioned, without any enamel band. Longitudinal furrows are present on the proximal part, which is expected for the genus Mammut. These characteristics are morphologically comparable with the NKP-1 upper tusk and the Abkhareh one, but the dimensions of the Milia upper tusks are larger than the NKP-1 and Abkhareh ones.
Upper tusks of “ Mammut ” borsoni and “ Mammut ” obliquelophus differ from those of Zygolophodon turicensis by lacking of enamel band. Upper tusks of the genus “ Mammut ” are straight or upturned, and lower tusks are relatively small or even vestigial.
The tusks of Zygolophodon turicensis are not twisted. They are characterized by ellipsoid cross sections and straight or anteroventral located enamel bands (Tassy 1977, 2013, 2014).
Proboscideans known from the Late Miocene of the Northwest of Iran include the deinotheriid Deinotherium, the choerolophodontid C hoerolophodon, the amebelodontid Konobelodon, and the mammutid “ Mammut ”. The morphology of the tusks of Abkhareh, Varzeghan is obviously dissimilar from the strongly curved and robust lower tusks of Deinotherium (e.g., Tassy, 2016). According to Harris (1978), the mandibular tusks of Deinotherium are relatively short (e.g., the mandibular tusk belonging to a very large individual of D. gigantissimum from Pripiceni, Moldova, with 978 mm, which is still short in comparison with Abkhareh tusks; see Harris, 1978) and recurved below symphysis and are almost vertically aligned. Normally, adult deinotheres tusks terminate in rounded conical points. Also, lower tusks of Deinotherium often show no signs of wear (Delmer, 2005), which contrasts with the Abkhareh tusks. However, wear facets have been observed in a few deinotheriid individuals. They are found on the anteromedial tip, suggesting wear by abrasion against one object in front of and between the tusks (Harris, 1978). So, it is supposed that the tusks of Abkhareh can be allocated to an upper tusk of an elephantoid sensu (Tassy, 1988), clade Mammutida (Elephantida, proboscideans) (Shoshani, 1996a, 2002).
Moreover, Choerolophodon, which is recognizable based on its strong curvature and double twisted (outwards and upwards) upper tusks, is markedly different from Abkhareh tusks. Konobelodon has less curved upper tusks than the Abkhareh one and no torsion (Pestszentlörinc, Hungry, HNHM-V.79.34; Konidaris & Tsoukala, 2020 Schlesinger, 1922).
Dental comparison
The cranium Kubiak (1972) described has two upper molar teeth: M2, M3. The M2 is trilophodont, complete, but deeply worn down. The third molar is broken, and only the 1st and 2nd lophs are preserved. The anterior lophs are relatively worn. There are no conules between ridges in Kubiak’s M3 material, and half lophs are almost symmetrical in width but not in morphology. It seems that the first pretrite loph and the first posttrite loph consist of two or three mesoconelets, which are relatively worn. However, the morphology of the first and second lophs of M3 from Balta Sands (Podolia, Ukraine, Kubiak, 1972, pl. XII, Fig. 7) is almost similar to the Abkhareh M3. So, the assignments of the Abkhareh tooth to “ Mammut ” cf. “ M.” obliquelophus can be based on its zygodont morphology and its similarity to the Kubiak material.
According to Titov and Tesakov’s study (2013), " M. " obliquelophus was reported in several Turolian (Late Miocene) vertebrate faunas in Southwestern Russia. These materials were discovered in Morskaya 2 (middle Turolian, MN12–MN13?), and include an incomplete mandible with m 1 -m 3 tooth rows and small, relatively straight lower tusks. The materials were attributed to " Mammut " cf. obliquelophus Mucha, 1980, due to their morphology resembling that of mastodon molars, relatively straight lower tusks, and medium-sized symphysis (Titov and Tesakov, 2013, Fig. 24.3, b–d).
Also, a left third upper molar of Yanovka-Obokhovka Sand pits deposits dated to Lower Pontian (MN12) in Russia (specimen NMIDK KP-10589/P-89, collection Novocherkassk housed in History Museum of Don Cossacks) has close similarity with European Turolian zygodont mastodons attributed by Markov (2008) to “ M. ” obliquelophus. The tooth shows close morphological correspondence with upper third molar from Abkhareh, Iran submitted in this study (see Titov and Tesakov, 2013, Fig. 24.3, e). The first loph of M 3 from Yanovka-Obukhovka is missing, and the antero-labial part of the second one is damaged. The third and fourth lophs are preserved enough, revealing clear zygodont characters. The length of the remaining fragments is more than 120 mm, and the width of the second loph is about 88 mm, which is almost comparable with that of the Abkhareh one, with 194 mm in length and 91.5 mm in width. The lophs are sharp-crested especially it is obvious in the third and fourth lophs, which are slightly worn. All the synclines separating the lophs are open and not blocked by conules. Pretrite conules (crescentoids) are almost completely reduced, and posterior cingulum is crenelated but low. All of these characteristics are almost similar to M 3 from Abkhareh. Both molars of Abkhareh and Yanovka-Obukhovka reveal crested lophs, reduced crescentoids, and zygolophodon crests especially on posterior slops of posttrite main cusps.
The two M 3 distal fragments (TCM 19355/C and 19255/D) from P ǎ gaia, Bihor District in NW Romania are assigned to Mammut praetypicum (Schlesinger, 1919) by Codrea et al., 2005 (Pl. I, Fig. 4). They show morphological similarity with Abkhareh cheek teeth. Although both are broken, and some parts of the anterior lophs are missing, they are preserved enough to reveal zygodont characteristics.
“ Mammut ” borsoni and “ Mammut ” obliquelophus have molars with larger width in comparison with Zygolophodon turicensis. Cheek teeth of the genus “ Mammut ” express open valleys without additional conules, a distinguishing trait seen in more derived Mammut, whereas the molars of Zygolophodon show a more bunodont character (Tobien, 1996). According to Garevski et al. (2012), “Height of the lophids about their anteroposterior length and the lingual cingulum height is a character distinguishing Zygolophodon turicensis from the derived mammutid “ Mammut ” borsoni and related forms”
According to Duangkrayom et al. (2016), the upper third left molar PRY200 from the Late Miocene Tha Chang sand pits, Nakhon Ratchasima, North-Eastern Thailand is attributed to Zygolophodon sp. The molar teeth has four lophs plus an anterior cingulum and a posterior cingulum. It is clearly smaller than M3 of Abkhareh. The Tha Chang molar is 152.5 mm in length and 80.8 mm in width and is seemingly smaller than “ Mammut ” borsoni molars measured by Tobien et al. (1988). Although crescentoids are present in both Zygolophodon and “ Mammut ”, The Abkhareh M 3 has stronger zygodont crests and pretrite adaxial conelets. The fourth loph in both specimens from Abkhareh and Tha Chang is well-developed, but the anterior and posterior cingulum in Tha Chang M 3 is more reduced than that of Abkhareh M 3.
description: Published as part of Yaghoubi, Sadaf, Ashouri, Ali Reza, Ataabadi, Majid Mirzaie & Ghaderi, Abbas, 2024, First true mastodon from the Late Miocene of Iran, pp. 1-13 in Swiss Journal of Palaeontology (15) (15) 143 (1) on pages 3-9, DOI: 10.1186/s13358-023-00300-7, http://zenodo.org/record/12005290