Supervisors info:
Σωκράτης Ρουσιάκης, Επίκουρος Καθηγητής, Τμήμα Γεωλογίας και Γεωπεριβάλλοντος, Εθνικό Καποδιστριακό Πανεπιστήμιο Αθηνών
Δημήτριος Κωστόπουλος, Καθηγητής, Τμήμα Γεωλογίας, Αριστοτέλειο Πανεπιστήμιο Θεσσαλονίκης
Γεώργιος Ηλιόπουλος, Αναπληρωτής Καθηγητής, Τμήμα Γεωλογίας, Πανεπιστήμιο Πατρών
Summary:
This Thesis deals with the palaeoecology of the fossil carnivorans of Greece and, in particular, with their diet. Carnivora don’t eat exclusively meat, but they frequently are omnivores, insectivores or even herbivores. In this study extant Carnivora were divided into 12 dietary categories. The studied fossil material belongs to 47 species from 8 families, coming from two periods of geological time: the Late Miocene (11.6-5.3 Mya) and the Villafranchian (3.5.-0.8 Mya). These periods include some of the richest fossiliferous localities in Greece, providing enough material to apply the necessary methods. To test the made assumptions, a comparative sample of 75 species belonging to 13 families of extant carnivorans was used.
The main focus of this work is to calculate a number of proxies which are connected to the diet of these species. The proxies studied here were: bite force, upper canines’ and incisors’ bending strength, endocranial volume, relative rostrum width, mastoid musculature, dental mesowear, dental carnassial and grinding surfaces, dental intercuspid notches and dental morphology in general. All these parameters are combined, in order to extract a more accurate result.
The first chapter of the results concerns the diets of some enigmatic species. Indarctos atticus resulted to be an omnivore, based mostly on plant material. Ursus etruscus, Ursavus ehrenbergi and Ursavus depereti were found being opportunistic omnivores. Simocyon primigenius resulted being probably a scavenger, but also a predator of small-medium sized mammals and probably completed its diet with a small amount of plants. A similar niche, without the ability of bone-cracking, is proposed for Plesiogulo crassa. Baranogale helbingi resulted to be a meat-based omnivore, similar to extant martens.
The second chapter of the results deals with the coexistence of species that seem to have a similar ecology. The first part were the Crocuta-like hyenas of the Turolian (Adcrocuta eximia, Lycyaena chaeretis and Belbus beaumonti). It was found that Adcrocuta is so dominant over the other species because it was larger, more robust, better adapted to bone-cracking and probably social, resulting to lower abundances forthe other two genera. The next case were the ictitheres of Late Miocene (Plioviverrops orbignyi, Protictitherium crassum, Ictitherium viverrinum and Hyaenotherium wongii). The first two genera were found to be opportunistic insectivores-omnivores. However the other two genera seem to have a similar ecological niche, with Hyaenotherium being more carnivorous and Ictitherium being more opportunistic. This niche overlapping is probably the cause for their distinct biogeography, with Ictitherium thriving in Pikermi and Hyaenotherium in Samos. The third case of coexistence was the felids of Pikermi (Pristifelis attica, Metailurus parvulus, Metailurus major, Paramachairodus orientalis and Amphimachairodus giganteus). These species were able to coexist, because they did not have the same body size. Therefore, their prey also had a relevant body size. The only species of the same size were Paramachairodus and Metailurus major, which represent two different evolutionary stages of sabertooths. Thus, these two taxa must have been competitive with each other and maybe that’s the reason for their infrequency. Another part was the small-sized mustelids of Turolian (Martes woodwardi, Promeles palaeattica, Promephitis lartetii, Parataxidea maraghana, Sinictis pentelici and a new species of mustelid). These species seemed to cover similar niches and having similar body sizes, with the exception of the smaller Promephitis. Probably this is the reason for their low abundance and the distinct biogeography of Promeles and Parataxidea (present in Pikermi and Samos respectively). The fifth case was the coexistence of the sabertooths Homotherium and Megantereon in the Villafranchian. It seems that this coexistence was possible due to the size difference between the two taxa and because of their different hunting strategies, since Homotherium was more cursorial and probably didn’t make an instant canine-shear bite as Megantereon. A similar case can be seen with Chasmaporthetes lunensis and Pliohyaena perrieri, with the former being a social and cursorial hunter and the latter being a solitary scavenger. The last case of coexistence were the canids of Apollonia (Vulpes praeglacialis, Lycaon lycaonoides, Canis arnensis, Canis etruscus and Canis apolloniensis). Vulpes praeglacialis occupied a niche similar to extant foxes and Lycaon similar to extant wolves. The other three canids probably represent a gradual transition from a form similar to jackal (Canis arnensis) to a form similar to a small wolf (Canis etruscus) with Canis apolloniensis being the intermediate stage. This coexistence of three species of canids probably led to interspecific competition between them.
The third chapter of results dealt with the temporal alternation (or no alternation) of some phylogenetic lines. The first case was the transition Promeles palaeattica - Meles dimitrius - Meles meles. This lineage seems to adapt to a more plant-based diet and an increase in size. The second line was that of Nyctereutes: N. donnezani - N. megamastoides - N. procyonoides. This line also moved to a more plant-based omnivory, but this time the body size of the species was reduced. The next two cases dealt with two lineages that had similar representatives in the fossil record of Greece from the Miocene until the Late Pleistocene. The first lineage was that of Crocuta-like bone-crushing hyenas: Dinocrocuta Adcrocuta Pliohyaena Pachycrocuta Crocuta and the second was that of large felids Amphimachairodus / Paramachairodus / Metailurus major - Homotherium / Megantereon / Panthera gombaszoegensis - Panthera leo / pardus.
Finally, the dietary category for every species was defined in a table and a suggestion for its possible prey genera (based on its already known associated faunas) was made, accompanied with the reference of a modern analogue species.
