Homo bodoensis, Roksandic & Radović & Wu & Bae, 2021

Roksandic, Mirjana, Radović, Predrag, Wu, Xiu-Jie & Bae, Christopher J., 2022, Resolving the “ muddle in the middle ”: The case for Homo bodoensis sp. nov., Evolutionary Anthropology 31 (1), pp. 20-29 : 5-6

Homo bodoensis sp. nov.

Etymology: The name bodoensis refers to the site of Bodo D'ar where the fossil specimen Bodo 1 was discovered. 123

Holotype: Bodo 1, a partial cranium of an adult (presumably male) individual, preserving the face and the anterior braincase, found in autumn 1976 by Alemayehu Asfaw, Paul Whitehead and other members of the Rift Valley Research Mission in Ethiopia headed by Jon Kalb. 123,124 The specimen is currently curated in the National Museum of Ethiopia in Addis Ababa, Ethiopia. H. bodoensis has been deposited in the ZooBank database (http://zoobank.org/) with Life Science Identifier urn:lsid:zoobank.org:act:50AC3EA4-82E0-4AAD-BCDA-6DE6055888A7.

Description (modified from References 20,30,35,123,125): Bodo 1 comprises a damaged facial skeleton, partial neurocranium, and basicranium anterior to the basion of a single individual, reconstructed from dozens of individual bone fragments ( Figure 2 ). Aside from the fact that the lateral portion of the right maxilla, the right zygomatic bone, and the left temporal process are missing, the face is generally well preserved. The palate is missing the portion posterior to the P4, and except for some small fragments of the right molar roots, the teeth are not preserved, and the alveolar processes show damage. The neurocranium preserves an almost complete frontal bone, the sphenoid, parts of the left temporal and both parietals, and the right portion of the occipital bone. The basicranial portion includes the partially preserved left mandibular fossa and articular eminence, the basioccipital, and the petrous portion of the temporal bone. The face is strikingly massive, with large rectangular orbits and a very broad interorbital region, a wide nasal root and aperture, a deep and robust left zygomatic, and a broad and deep palate. Though projecting and heavily built, the supraorbital tori are arched, segmented (i.e., divided into medial and lateral segments), and attenuated laterally; they do not form a continuous bony shelf but are rather separated by a prominent glabellar region, behind which is a flattened plane (rather than a sulcus). There is a distinct sagittal keeling in the frontal view, especially in the bregmatic region of the vault. The maxillary sinus is expanded, and there is no canine fossa. The frontal sinuses are also extensive and asymmetrical (the right sinus is larger). In lateral view, the skull is long and low, and the frontal presents a low and flattened profile. There is a prominent parietal angular torus, and the temporal squama is high and arched. The anterior nasal aperture is almost vertical in the lateral projection. In the superior view, the skull presents a piriform shape, broadening posteriorly from the noticeable postorbital constriction. In the inferior view, the large incisive foramen is placed anterior on the hard palate, the mandibular fossa is shallow, and the preserved part of the articular eminence is flat; the petrous portion of the temporal is placed in such a way that the foramen lacerum displays a crevice-like configuration. The endocranial capacity was estimated to ~1250 cm 3 (i.e., between ~1200 and 1325 cm 3). 125 The series of cut marks situated on the facial and posterior parietal regions were interpreted as intentional postmortem defleshing. 126

Type locality: Bodo D'ar, the Middle Awash research area, Afar Depression, the northwestern part of the former Hararghe Province, Ethiopia.

Geological age and stratigraphic position: Upper Bodo Sand Unit. 123 Dated to ca. 600 ka by laser-fusion 40 Ar/ 39 Ar technique (0.64 ± 0.03 Ma), biostratigraphy and tephrochronology. 127

Archaeological context: The specimen is associated with an Acheulean stone tool assemblage. 123,125

Species diagnosis: The species is diagnosed by a unique combination of cranial traits. The Bodo specimen has already been described as showing a mix of H. erectus -like and H. sapiens -like features. 20,35, 123 The species is similar to H. erectus in having: a robustly built midface; total facial prognathism 128; projecting tori and a flattened low frontal squama; sagittal keeling; a low vault profile; a prominent parietal angular torus; thick vault bones; no foramen lacerum is observable — it is presented as a narrow crevice. 20,128 These traits can be linked to the retention of the general cranial structure from H. erectus . Traits similar to other Middle Pleistocene and later hominin taxa include: increased cranial capacity and associated traits (broader frontal and mid-vault, reduced postorbital constriction, signs of parietal bossing, high and arched temporal squama), a vertical (rather than forward sloping) nasal margin, and the position of the incisive canal in front of the hard palate. 20,99, 128 Excessively thick and projecting, but segmented brow ridges, with the incipient division of the brow at midorbit and attenuated laterally may be considered a distinctive trait of the species.

Comparisons: In comparison to H. erectu s, H. bodoensis differs by the increased cranial capacity (intermediate between H. erectus and H. sapiens ) and a suite of associated derived traits: the curvature of the temporal squama; broader mid-vault; signs of parietal bossing; and relatively broad frontal bone where the maximal cranial breadth lies above the lower third of the skull in posterior view, with more vertical parietal walls.

Increased cranial capacity is shared among most of the Middle Pleistocene hominins (excluding H. naledi and island isolates of Southeast Asia such as H. floresiensis ). This trait is presumably already under selection in the MRCA in the latter portion of the Early Pleistocene. 107,129 Other features are not shared with Middle Pleistocene hominins such as H. neanderthalensis , late H. erectus , and potentially other Asian groups yet to be systematized. The species differs from H. neanderthalensis as it does not show any of the Neanderthal-specific morphology associated with midfacial prognathism and neurocranial shape. It also differs in the particular form of the brow ridges, which are smoothly continuous and double-arched in H. neanderthalensis . 32

H. bodoensis lacks a number of the H. sapien s specific features — warranting a separate species designation. This is contrary to what is observed in H. neanderthalensis where the autapomorphies emerge early in the Middle Pleistocene. However, all of the later H. sapiens specific features can be derived from traits present in H. bodoensis , including the massive but segmented (divided into lateral and medial parts) browridges. 20,34

Hypodigm: In addition to the holotype Bodo 1, the hypodigm is based on the sufficiently preserved cranial specimens with the exclusion of isolated mandibles and includes at a minimum: Kabwe 1 (Broken Hill), Ndutu, Saldanha (Elandsfontein), Ngaloba (LH 18), and potentially Salé in Africa. 30,108, 130 – 135 Kabwe 1 could represent a late survivor of the taxon. 136 Some Middle Pleistocene specimens from Europe (e.g., Ceprano calvarium 137,138), could be included in this group as well. Locations, dating, previous taxonomic designations, and references for the included specimens are provided in the Table S1.

Distribution: The species had a pan-African distribution with the peripheral range extending into the eastern Mediterranean (Southeast Europe and the Levant) from which it could have contributed to the repopulation of European (and possibly Central and East Asian) demographic sinks after the glaciations.

Figures

FIGURE 2 Homo bodoensis sp. nov. holotype partial cranium Bodo 1 (Middle Awash, Ethiopia). Frontal (a), left lateral (b), superior (c) inferior (d) views. Scale bar: 5 cm. Source: Original photos Copyright © Jeffrey H. Schwartz