Wednesday, May 30, 2007

Locomotor behavior of Paradolichopithecus arvernensis as inferred from the functional morphology of its ankle and elbow

Taking all ankle and elbow elements of Paradolichopithecus into account, the picture emerges of a highly terrestrial monkey. This is not surprising as many fossil cercopithecines are found in open country habitats and show terrestrial adaptations, such as Dinopithecus (Late Pliocene, Africa), Procynocephalus (Late Pliocene, China and India), Paradolichopithecus (Pliocene, Spain and Asia), Theropithecus (Middle Pleistocene - Holocene, Africa) and, among the colobines, Paracolobus (Pliocene, East Africa) and Dolichopithecus (Pliocene, Europa) (Szalay & Delson, 1979). In addition, the larger species tend to be terrestrial, possibly as a response to predator pressure. This, too, makes a terrestrial adaptation of our large Paradolichopithecus very probable.
Body weight was carried more posterior, as the architecture of the olecranon and the trochlear notch are less apted for sustaining heavy load than is the case in the extant baboons. The morphology of the arm indicates an increased mobility in the elbow joint, with a departure from the sagittal plane during flexion. Paradolichopithecus could very well have used his strong arms for carrying food while walking or standing. Another option is the use of the arms in fights and defense.
The massive medial malleolus of the tibia also shows that a larger (part of the) body weight was carried on the hindlimbs. The suspensory facet for the fibular malleolus indicates an increased importance of the lateral malleolus in transferring body weight, and an increased fixation of the talus in the malleolar fork, formed by both the malleoli together.
As to the ankle joint, a remarkable parallel is seen with Australopithecus. Unique features that distinguish Paradolichopithecus, and probably also Procynocephalus, from the other papionins are seen also in Australopithecus, though the overall architecture of the Paradolichopithecus talus is typically cercopithecoid (pronounced lateral trochlear ridge, hardly developed groove for large toe flexor), whereas it is typically hominoid for Australopithecus (symmetrical trochlea, pronounced large toe flexor).The terrestrial traits in the postcranial elements show that this large monkey was clearly adapted to the habitat: an open savanna/bushland environment with seasonal availability of food, and large distances between the food sources.

Read more in SONDAAR P.Y., VAN DER GEER A.A.E., DERMITZAKIS M. (2006). The unique postcranial of the Old World monkey Paradolichopithecus: more similar to Australopithecus than to baboons. Hellenic Journal of Geosciences 41, 1: 19-28. Special volume in the memory of P.Y. Sondaar

and in VAN DER GEER A.A.E., SONDAAR P.Y. (2002). The postcranial elements of Paradolichopithecus arvernensis (Primates, Cercopithecidae, Papionini) from Lesvos, Greece. Annales Géologiques des Pays Helléniques 1e Série 39, A: 71-86. Free pdf at .

and in SONDAAR P.Y., VAN DER GEER A.A.E. (2002). Arboreal and terrestrial traits as revealed by the primate ankle joint. Annales Géologiques des Pays Helléniques 1e Série 39, A: 87-98. Free pdf at .

Thursday, May 24, 2007

The postcranial of the deer Hoplitomeryx (Mio-Pliocene; Italy): another example of adaptive radiation on Eastern Mediterranean Islands.

During the Late Miocene a highly endemic vertebrate fauna evolved on Gargano Island (south-east coast of Italy), comprising others the giant soricid Deinogalerix, the giant barn owl Tyto gigantea, the giant hamster Hattomys, and the 'prongdeer' Hoplitomeryx with five horns and sabrelike ('moschid' type) upper canines. The Hoplitomeryx skeletal material forms a heterogenous group, containing four size groups; within the size groups different morphotypes may be present. All size groups share the same typical Hoplitomeryx features. These are: one central nasal horn and a pair of pronged orbital horns, protruding canines, complete fusion of the navicocuboid with the metatarsal, distally closed metatarsal gully, a non-parallel-sided astragalus, and an elongated patella. The different size groups are equally distributed over the excavated fissures, and are therefore not to be considered chronotypes. The hypothesis of an archipelago consisting of different islands each with its own morphotype cannot be confirmed.
The situation with several co-existing morphotypes on an island is paralleled by Candiacervus (Late Pleistocene, Crete, Greece). Opinions about its taxonomy differ, and at present two models prevail: one genus for eight morphotypes, or alternatively, two genera for five species. The second model is based upon limb proportions only, but these are invalid taxonomic features for island endemics, as they change under influence of environmental factors that differ from the mainland. Also in Hoplitomeryx the morphotypes differ in limb proportions, but here different ancestors are unlikely, because in that case they all ancestors must have shared the typical hoplitomerycid features. The morphosphere of Hoplitomeryx is too coherent to assume two or more different ancestors, and indicates a monophyletic origin of all morphotypes.
The large variation is instead explained as an example of adaptive radiation, starting when the Miocene ancestor colonized the island. The range of empty niches promoted its radiation into several trophic types, yielding a differentiation in Hoplitomeryx. The shared lack of large mammalian predators and the limited amount of food in all niches promoted the development of derived features in all size groups (apomorphies).

For full text, see VAN DER GEER, A.A.E. (2005). The postcranial of the deer Hoplitomeryx (Mio-Pliocene; Italy): another example of adaptive radiation on Eastern Mediterranean Islands.van der Geer. Monografies de la Societat d'Història Natural de les Balears 12: 325-336. Palma de Mallorca. For a free pdf [1,018 kb]: See my website for three more publications on this bizarre and enigmatic insular 'deer' of the Late Miocene.

For more general information of this enigmatic Late Miocene 'deer', see my Wikipedia page at

New data on the Late Pleistocene Cretan deer Candiacervus sp. II

For our museum, we mounted a skeleton of the endemic Late Pleistocene Cretan deer Candiacervus sp. II (Liko Cave), using bones of different individuals. This composite skeleton contributes to the study of taxonomy of insular ungulates as it reveals some additional features that were not detected in the isolated elements. Candiacervus sp. II differs from all known recent and extinct mainland deer, mainly in its proportions. Although its considerably shortened distal limbs were already noted in the past, Candiacervus sp. II now appears at the same time to have had a more or less normal vertebral column length relative to continental large deer, and moderately upwards curved lumbar section, both features reminding us more of the insular dwarf bovid Myotragus than of the mainland small deer Axis axis. Combined with an increased massivity of all bones and pronounced muscle scars, this change in body proportions appears to indicate that Candiacervus sp. II evolved towards the niche of goat-like bovids in rocky environments. Other additional diagnostic features are the horizontally directed transversal processus of the vertebras, fusion of the lateral metacarpal to the main metacarpal, a tail length of ten vertebras, a more pronounced difference between anterior and posterior hooves, and the presence of lateral toes upto the third phalanx, anterior as well as posterior.

Read more in VAN DER GEER A.A.E., DE VOS J., LYRAS G.A., DERMITZAKIS M.D. (2006). New data on the Pleistocene Cretan deer Candiacervus sp. II (Mammalia, Cervinae). Courier Forschungsinstitut Senckenberg 256: 131-137. For a pdf, send an e-mail to For more Candiacervus publications, visit our websites at and

For more general info on the extinct Cretan deer, see

The unique postcranial of the extinct Old World monkey Paradolichopithecus

The talus (astragalus), distal tibia and the humerus of Paradolichopithecus arvernensis show some unique features, not seen in other monkeys.
The humerus has an increased articulation area on the head compared to Papio, a wide and deep groove for the biceps tendon, a gradually descending capitulum, and an oblique axis for flexion-extension through the elbow joint. During flexion, the ulna deviates from the parasagittal plane, and ends in a position medially to the humerus instead of parallel above it, due to the trochlear shape and axis. This unique feature yields a significant increased mobility.
The distal tibia bears a more massive, square and blunt malleolus that lacks the typically pronounced ball-shaped area, a wider groove (sulcus malleolaris) for the tendon of the M. tibialis posterior, a more square cross-section, clear scars for the fibula, and a double tendon groove on the dorsal surface (either for a bifurcated tendon for the M. flexorum tibialis posterior or a pronounced groove for the long toe flexor), which follows the parasagittal plane. None of these features is unique, and they make Paradolichopithecus resemble Australopithecus, a trained Japanese macaque and to a lesser extent some other macaques. The combination indicates a maintainance of the close-packed situation from dorsiflexion to plantar flexion, an increased importance of the fibula in weight transfer, a stronger plantar flexion, and possibly a slightly abducted foot. The flat tibial malleolus in Paradolichopithecus and Australopithecus, compared to baboons (Papio) and chimps (Pan) respectively, in combination with the corresponding facet on the talus acts as a blocking mechanism, preventing further dorsiflexion rotation during maximal dorsiflexion. This makes this ankle unsuitable for climbing.
The talus has an almost parallel trochlea, a large flap-like, protruding fibular suspensory facet, and a slightly deeper facet for the spring ligament on the talar head. These features are suggestive for a baboon-like ankle joint with the body weight more evenly distributed over the talar trochlea, a greater proportion of the weight transfer through the lateral (fibular) side, and with approximate the same stability in maximal dorsiflexion as in maximal plantar flexion. In these aspects Paradolichopithecus resembles Australopithecus.
Considering the unique features of the ankle and elbow of Paradolichopithecus, it may be expected that its locomotion differed from that of baboons. Main differences are the increased fibular component, the increased stability in plantar flexion, a more evenly distribution of stability during locomotion, and an equal medio-lateral stability in maximal plantiflexion and in maximal dorsiflexion. In our view, such a type of locomotion finds a parallel in Australopithecus and in trained Japanese macaques. The latter appear to develop significant modifications during training, especially in the hind limb, to satisfy the functional requirements for increased habitual bipedalism. Amongst others, the malleolus of the tibia has been remodeled under the influence of the greater stress and became less cusp-shaped, and the talar malleolar facet correspondingly more planar. The varus knee in the trained macaque further requires an increased fibular compound. This may have its parallel in Paradolichopithecus and Australopithecus, in whom we also find an increased fibular component. It should be stressed, however, that the kind of bipedalism of the trained macaque differs essentially from the striding gait bipedalism with erect trunk and straight knees of the genus Homo. The macaque bipedalism is characterised by high energy cost and bent knees. Considering the similar biomechanical features in Paradolichopithecus, Australopithecus and the trained macaque, it is tempting to conclude that also the two former genera had an all-round, energetically expensive bipedal mode with bent knees. This development then was not restricted to the hominoid clade, but appeared also in the papionins, as evidenced by the difference between Australopithecus and Pan on one hand and Paradolichopithecus and Papio on the other hand. The pattern shared indicates similar mechanical stresses, and reflects a shared increased frequency of bipedalism in the daily locomotor behavior, possibly but not necessarily, accompagnied by an increased mobility of the arm.

Read more in SONDAAR P.Y., VAN DER GEER A.A.E., DERMITZAKIS M.D. (2006). The unique postcranial of the Old World monkey Paradolichopithecus: more similar to Australopithecus than to baboons. Hellenic Journal of Geosciences 41, 1: 19-28. Special volume in the memory of Paul Yves Sondaar. Free pdf [868 kb] at

Origin and adaptation of Cynotherium sardous (Mammalia: Carnivora) by Lyras, Van der Geer, Dermitzakis, De Vos in JVP 26 (3): 735-745

The endemic insular canid Cynotherium sardous is known for one and a half century, yet its phylogenetic position remained unsolved. This was because inherited ancestral characters and acquired adaptations to different ecological pressures could not be separated. Morphological and biometrical data alone are therefore insufficient. In this study the problem is approached again, with the use of morphological features that were either overlooked or could not be explained properly, in combination with results from recent major revisions of canid phylogeny. It appears that Xenocyon is the most parsimonious ancestor of Cynotherium, and that this large hypercarnivorous canid, once on the island, faced a rather different menu consisting of small prey only. The subsequent necessary adaptation resulted in a small-sized dog which carried its head much in the way foxes do and was able to hold its body low to the ground and move its head laterally better than any living canid. Its dentition and brain morphology remained much the same, whereas its skull lost the typical fortifications seen in the other hypercarnivorous canids; these are considered superfluous for Cynotherium who had to exchange big and strong prey for small and fast prey.

Read the full text in LYRAS G.A., VAN DER GEER A.A.E., DERMITZAKIS M.D., DE VOS J. (2006). Cynotherium sardous, an insular canid (Mammalia: Carnivora) from the Pleistocene of Sardinia, and its origin. Journal of Vertebrate Paleontology 26(3): 735-745,

and in LYRAS G.A., VAN DER GEER A.A.E. (2006). Adaptations of the Pleistocene island canid Cynotherium sardous (Sardinia, Italy) for hunting small prey. Cranium 23 (1): 51-60 (for pdf, click )

For pdf's, ask me at or ask, or visit our pages: and and select Publications

Crete before the Cretans: the reign of dwarfs

Crete was completely submerged during the Pliocene, and gradually emerged in the Early Pleistocene. New and empty islands like these are normally colonized overseas by sweepstake dispersal, which means that only a limited number of taxa is able to reach the island. This results in an unbalanced mammal fauna, as a rule consisting of only elephants, hippopotamus, deer, cattle, rodents, insectivores and sometimes otters. After successful colonization, as a rule a fast evolutionary change takes place, which can be explained as an adaptation to the restricted island environment. As a result, island faunas are very different from mainland faunas, but similar to each other. Crete is no exception to this general pattern, and during the Pleistocene there were two successive endemic mammalian faunas. The first (the Kritimys-biozone) is characterised by a dwarf mammoth, a dwarf hippopotamus and a giant mouse. The second (the Mus-biozone) is characterised by a dwarf elephant, a dwarf deer (next to medium and large-sized deer) and a large mouse. The reason for the dramatic faunal turnover between the two biozones is unknown, but may very well have been related to a significant sea-level drop. This decreases the distance between the now larger island and another firm ground. The second fauna got extinct just before or after the arrival of the first humans. Problems of dating and the lack of paleolithic artefacts or human remains obscures this point. In any case the fauna of the second biozone was already completely extinct at Aceramic Neolithic and Minoan times, and replaced by newcomers who came together or along with the humans.

Read more in VAN DER GEER A.A.E., DERMITZAKIS M., DE VOS J. (2006). Crete before the Cretans: the reign of dwarfs. Pharos 13: 121-132. Netherlands Institute at Athens, Greece. Free pdf [ 2,197 kb] at .

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