Hyena coprolites and palaeoecology

Introduction

Hyena coprolites are a reliable source of evidence for species identification, animal diet, patterns of use of the environment, and animal-human relations in the past. Some hyena species digest bone fragments which are then passed out through the faecal material. However, the bone fragments are much too small to identify faunal species. Pollen, grass, and insects are preserved in hyena coprolites as well. Coprolite palynology (the study of pollen) is important for palaeoecology reconstructions as pollen can be used to interpret palaeovegetation and to infer palaeoclimatic conditions. Reconstructing the palaeoecology from hyena coprolites can be determined by comparisons made between extant hyena faecal remains and hyena coprolites from the fossil record.

Distinguishing hominin from hyena bone accumulations

Hyena coprolites are a good source of evidence for hyena-hominin relations. Hyenas tend to produce taphonomic signatures of damage on bones which can be misinterpreted as hominin-made. In order to circumvent this problem of misinterpretation, various methods are utilized by researches to determine the primary accumulating agent of a particular assemblage. There are various criteria used to distinguish hominin from hyena bone accumulations. These criteria can be used to determine whether a bone accumulation is the result of hyena or hominin activities. These criteria include the presence of distinct hyena damage on bone surfaces as well as the presence of particular bones characteristic of hyena feeding preferences. When these criteria fail to distinguish hyena from hominin accumulations, the presence of hyena coprolites may serve as a direct taphonomic signature of hyena accumulation.

A Scientific Approach

In order to determine the significance of hyena coprolites for palaeoecology reconstructions various scientific approaches are needed for coprolite analysis. Comparative studies between hyena coprolites and faecal material of extant hyenas provides an understanding of coprolite composition, hyena diet, as well as the use of coprolites as ecological indicators. Additional research of hyena coprolites utilizes macroscopic and microscopic analysis. Macroscopic analysis includes the evaluation of the colour, shape, and size of the coprolite. This is useful for species identification as well as the age profile (adult or juvenile) of the individual. Microscopic analysis includes the evaluation of the composition of the coprolite which is useful for environmental reconstructions. Microscopic analysis of hyena coprolites is useful for identifying pollen samples within the coprolite which can then be used for direct environmental reconstructions.

Coprolites as pollen traps

Hyena coprolites preserve pollen very well as they are hard and durable. Pollen in hyena coprolites reflects the vegetation of the regional environments in which hyenas are active. Hyenas digest sufficient organic and plant material that is preserved in their faecal matter. It is therefore possible to use the contents preserved in hyena coprolites for palaeoecology reconstructions. Hyenas incorporate pollen through various ways. Airborne pollen from the surrounding vegetation can be incorporated into diet; pollen in water may also be consumed; flowers, grasses, leaves, fruits, and seeds are directly consumed and therefore account for the pollen in hyena diet as well. Hyenas may also consume pollen from the stomach contents of their prey.

Taphonomic research provides insight into the manner in which pollen is consumed and implications for palaeoecological reconstructions. Behavioural ecology of a particular species, for example, may provide insight into the accumulation of pollen. Most hyenas will try to eat almost everything, and subsist on a broad-sized omnivorous diet including reptiles, vegetable matter, mammals, and bird eggs. Brown hyenas may even consume grass. When there is abundant supply of food resources, hyenas particularly the spotted hyena, may subsist primarily on meat, with preference for large mammals. In this case, the primary pollen source is the stomach content of the prey.

South Africa

Equus Cave, Northern Cape Province

Equus Cave is located near Taung in the Northern Cape Province. The cave yielded an abundance of well preserved bones and coprolites. The fossils have been interpreted as hyena accumulations during the Pleistocene and Holocene. The pollen derived from hyena coprolites is reflective of hyena diet as well as the environments occupied by the hyenas. Comparative studies have demonstrated that pollen is a good predictor of palaeoecology. Pollen from the Equus Cave hyena coprolites reflects shifts in vegetation from open grassland with some shrubs and trees during the late Pleistocene, to open savanna with the increasing appearance of shrubs, to modern savanna conditions in the last 7500 years. The mammalian bones were probably collected by hyenas using the cave for shelter. Scott argues that the brown hyena (''Hyaena brunnea''), rather than the spotted hyena (''Crocuta crocuta''), most likely occupied Equus cave and was therefore responsible for the bone and coprolite accumulations in the cave.

The pollen in the hyena coprolites at Equus Cave revealed a diversity of plant types with a continuous abundance of grass pollen throughout the sequence. The pollen in coprolites indicates distinct differences between the layers. The most evident difference is the change in low percentages of arboreal and high percentages of nonarboreal in the lower layers to high arboreal and low nonarboreal in the upper layers. The pollen ratio of arboreal versus nonarboreal shows an important shift from woody vegetation in lower level times to relatively open vegetation in upper level times. The pollen derived from the hyena coprolites is also indicative of climatic changes in the Pleistocene and Holocene. The lower level was deposited in the early Pleistocene under cool, moderately humid climatic conditions in which an open grassland with some shrubs persisted. The middle level was deposited during the late Pleistocene or early Holocene under warmer, drier climatic conditions which supported an open acacia savanna with an increasing appearance of shrubs. The upper level reveals thornveld vegetation.

Oyster Bay, Eastern Cape Province

Hyena coprolites from Oyster Bay, southeastern Cape coast, South Africa were found in association with mammalian bone assemblages that was accumulated by brown hyenas. The hyena coprolites were also associated with artifacts of the Howieson's Poort substage of the Middle Stone Age. Pollen assemblages in hyena coprolites are dominated by ''Myrica'', ''Stoebe-Elytropappus'' and ''Poaceae''. Today this vegetation occurs more inland. Comparisons with modern vegetation suggests that at the time of Howieson’s Poort occupation the environment had a complex mosaic of vegetation with cooler, more inland conditions than today.

San Teodoro Cave, Sicily

Fossil coprolites from the extinct spotted hyena, ''Crocuta crocuta spelaea'', in San Teodoro Cave, contains well preserved pollen grains which were used for vegetation reconstructions for the pre-Late Glacial. The pollen indicates that the vegetation was dominated by herbs with a reduced number of arboreal taxa. The coprolites are characterised by steppe taxa such as Poaceae, ''Artemisa'', ''Ephedra'', ''Chenopodiaceae'', and ''Asteraceae''. The pollen also indicates the reduced presence of arboreal, woodland taxa. A reconstruction of the landscape, using the coprolite pollen record shows the predominance, during the pre-Late Glacial, of a wooded steppe biome, with elements representing a variety of local environmental conditions.

Spain

Gabasa Cave Coprolites from the extinct spotted hyena, Crocuta crocuta spelaea, were used for pollen analysis in order to reconstruct the palaeoecology. The coprolites contain well preserved pollen assemblages. Pollen from the hyena coprolites indicate the development of a mosaic glacial landscape that included ''Pinus'' and ''Juniperus'' woodlands and steppes of ''Chenopodiaceae'', Poaceae, Artemisia, and Asteraceae.

Villacastín and Los Torrejones Hyena coprolites were recovered from the localities of Villacastín and Los Torrejones in central Spain. Pollen from the hyena coprolites complement the fossil record in suggesting a shifting mosaic of open and wooded habitats with abundant pine and juniper species, steppe-grassland areas with composites and chenopods, and enclaves with mixed oak forests.

Summary

Hyena coprolites can be used for palaeoecology reconstructions by providing information on animal diet and animal-human relations. Hyena coprolites preserve pollen which are good indicators of palaeoenvironment and vegetation. Coprolite palynology has proved its potential in recent studies for palaeoecology reconstructions and palaeoclimate inferences. Reconstructions the palaeoecology from hyena coprolites can be determined by comparisons made between extant hyena faecal remains and hyena coprolites from the fossil record as well as through macroscopic and microscopic analyses of the coprolites. Hyena coprolite studies at various sites in South Africa, Spain, and Italy have proven reliable in palaeoecology reconstructions.