Hyaenas and early humans in the latest Early Pleistocene of South-Western Europe

Throughout the Pleistocene, early humans and carnivores frequented caves and large rock-shelters, usually generating bone accumulations. The well-preserved late Early Pleistocene sedimentary sequence at Cueva Negra del Estrecho del Río Quípar (CNERQ) has provided substantial evidence concerning the behavioural and adaptive skills of early humans in Western Europe, such as butchery practices, lithic technology or tending fire, whilst also bearing witness to the bone-altering activities of carnivores. Recent fieldwork has allowed the re-examination of the spatial and taphonomical nature of the macrofaunal assemblage from the upper layers of Complex 2. These layers are somewhat different from most of the underlying sequence, in showing quite a high representation of cranial and post-cranial bones of large mammals, including several Megaloceros carthaginiensis antlers. The presence of Crocuta sp. at Cueva Negra represents one of the earliest instances of this genus in Western Eurasia. Identification of several juvenile Crocuta sp. remains alongside coprolites and bones with carnivore damage, indicates sporadical hyaenid denning activity. Furthermore, the presence of bones with percussion and cut-marks near to several hammerstones suggests a clear albeit limited anthropogenic input. We interpret the available taphonomical and spatial evidence from these layers as reflecting a multi-patterned palimpsest, likely representing the non-simultaneous and short-lived co-existence of hyaenas, humans, and other small carnivores in the Cueva Negra palaeolandscape during the final phase of sedimentation preserved at the site.

The assemblage shows a considerable degree of post-depositional fragmentation, with diagnostically dry fractures present in almost 20% of the assemblage, which further contributes to the high degree of fragmentation of the assemblage. This phenomenon artificially drives up the total number of remains and severely underplays the role of biological agents in relation to bone fracturing, thus resulting in a relatively low percentage of 6.5% for diagnostically green fractures in the assemblage; the origin of fractures in fragments <2cm is often hard to determine with accuracy.
Lying closest to the cave wall, metre-square C0e afforded an interesting pattern in terms of secondary taphonomical alterations, particularly in level 2f. 34.3 % of bones from this square show diagnostic dry fractures (n = 115), in contrast with the percentage of 19.6% for the assemblage as a whole. Furthermore, it also provided over 70% of the bones showing rodentgnawing (n = 25 for the whole assemblage). In this square, there was also a greater incidence of trampling, non-digestion biochemical alterations, and in situ authigenic mineral formation. Displacement of bones towards the end of the cave by non-sedimentary processes (e.g. trampling, rodent accumulation), could have favoured not only their accumulation, but also their subsequent exposure to physico-chemical processes, such as interaction of rainwater and the biocalcarenite of the cave wall, thereby leading to diagenetic alterations and postdepositional fragmentation of bone elements, and secondary mineral precipitation on some bone surfaces. Presence of gnawing marks on generally dry and weathered bone or antler fragments reflects a typical ethological pattern of several rodent species. It would be relevant to study in depth the morphology of the rodent tooth marks in order to discern the most likely species, given that some (e.g. porcupines) that engage with bones in this way also tend to accumulate them, so they could represent another contributing accumulation agent to the palimpsest under study.
The abundance of dry fractures, particularly in square (C0e), which is near the back of the rockshelter, together with the presence of weathering and rodent gnawing, alongside low levels of biochemical alterations and waterborne polishing, is noteworthy in the upper levels of Complex 2 of Cueva Negra, in stark contrast to the pattern found in other levels. Unit 6 in Complex 3-2, for example, shows a predominance of green fractures in a context of very low to non-existent weathering and high incidence of biochemical and non-abrasive waterborne alterations, in line with the general interpretation of the sedimentation pattern as the result of recurrent, lowenergy events that have yielded such a high-resolution sequence. Therefore, it is plausible that the upper levels of Complex 2 could represent a phase of slightly slower sedimentation rates over a non-geologically significant timescale, given the absence of palaeosol formation 1 . This phenomenon, alongside some degree of bioturbation detected at the micromorphological level 1 compatible with the burrowing activities of rodents and also hyaenas in their dens, likely favoured the generation of an archaeological palimpsest.

Figure S1.
Legend: Stratigraphic profile of Cueva Negra from the South Profile orthophotograph. Note the division and correlation of the sequence into both excavation units and geoarchaeological complexes.  Legend: Fragment of long bone diaphysis from a medium-sized herbivore with an impact negative from the dynamic loading of a percussive action. Photographic composition by Pedro Lucas Salcedo, and reproduced with permission.

Figure S4.
Legend: Phalanges displaying evidence of carnivore damage. Note the unfused proximal epiphysis of the second phalanx effects of digestion on the three associated phalanges of a juvenile cervid (unfused second phalanx, gastric acid pit on first phalanx). The first, second and third phalanges on top were found in spatial association and may well belong to the same individual. Picture taken by G.L.M. using Celestron Photoscan.

Figure S5.
Legend: Spatial distribution analysis of levels 2d, 2e, 2f in sectors C1 and C0. A─ PCA Kernel density for the totality of coordinated finds. B─ PCA Kernel density for bone elements. C─ PCA Kernel density for the totality of lithics and flakes and manuports-hammerstones distribution. D─ PCA Kernel density for bones with carnivore marks. E─ PCA Kernel density for the totality of bone pieces taking into account anatomical features. F─ Distribution of point by modulus (Spatial analysis performed with Arcmap "Spatial Analyst Tools", with visualisation using Inkscape.)
1a -4a: Spatial autocorrelation analysis using Moran's I from layers 2d, 2e, and 2f, in sectors C1 and C0 (see table S5). 1a─ totality of remains recorded, given the z-score = 21.9525967293, the probability is <1% that the pattern of grouping owes to random assortment. 2a─ totality of bone remains, given the z-score = 13.778122, the probability is <1% that the pattern of grouping owes to random assortment. 3a─ totality of bone remains showing carnivore marks, given the z-score = 10.2879, the probability is <1% that the pattern of grouping owes to random assortment. 4a─ totality of lithic remains recorded from layers 2d, 2e, and 2f, given the z-score = 6.7318, the probability is <1% that the pattern of grouping owes to random assortment.
1b -4b: Multi-distance spatial cluster analysis using Ripley´s K Function (see table S7). The computed confidence envelope = 999 permutations. Boundary correction method = Ripley edge correction formula. Number of distance bands = 10. 1b─ totality of remains from layers 2d, 2e, 2f. K-value > HiConfEnv, from which it follows that the spatial clustering is statistically significant. 2b─ totality of bone remains. The K-value exceeds the expected K-value, from which it is inferred that the pattern of spatial clustering is not necessarily of statistical significance. 3b─ totality of remains from layers 2d, 2e, and 2f that present carnivore marks. The K-value exceeds the expected K-value, from which it is inferred that the pattern of spatial clustering is not necessarily of statistical significance. 4b─ totality of lithic remains from layers 2d, 2e, and 2f. The K-value is below the expected K-value, reflecting a more dispersed distribution than expected for a random distribution over medium and long distances.
1c -4c and 1d -4d: Frequency graphs of probability density (vertical distribution), histogram and QQplot of standard normality. Statistical analysis was performed with Arcmap "Geostatistical Analyst Tools" and application of Gaussian approximation (see table S6). 1c-1d─ totality of georeferenced finds. The sample shows a normal distribution with a symmetrical unimodal Gaussian curve. 2c-2d─ totality of georeferenced bones. The sample shows a normal distribution with a symmetrical unimodal Gaussian curve, indicating presence of a single population in the sample. 3c-3d─ totality of bones showing carnivore marks. The sample shows a normal distribution for the sample with a bimodal curve indicating that one of the two populations present in the sample has a spread of variation different from the other one; in other words, the two peaks can be interpreted as reflecting both the noteworthy impingement of carnivores and the particularly low variation represented in the left-hand peak. 4c-4d─ totality of georeferenced lithic finds. The sample shows a normal distribution with a unimodal Gaussian curve, indicating presence of a single population in the sample. Legend: Taxonomical profile of the faunal assemblage from the upper levels of Complex 2 at Cueva Negra on the basis of MNI. The very high degree of assemblage fragmentation makes this metric the most reliable to assess overall taxonomic species composition in the assemblage, as opposed to MNE/NISP. NISP distribution per size class data is included in Tables 1 and S2.  Legend: Distribution of taphonomic alterations with regards to skeletal part in the faunal assemblage from the upper levels of Complex 2 (2c-2f) at CNERQ. Percentages in relation to NR. The limited incidence of biostratinomic alterations on small indeterminate remains reinforces the notion that post-depositional processes played a notable role in the fragmentation of this assemblage.

Table S4
Legend: Distribution of taphonomic alterations with regards to artificial stratigraphic layer in the faunal assemblage retrieved during the 2019 season from the upper levels of Complex 2 at Cueva Negra.   Legend: Statistical data from the Gaussian distribution and probabilistic frequency analysis for all coordinated remains (total), bone elements, bones with carnivore damage, and lithics. Layers 2d, 2e, 2f; 2019 field season.