Darwinius

Abstract: The mammalian order Primates made its first appearance in the fossil record during the Paleocene–Eocene thermal maximum (PETM), the global greenhouse warming event that marks the beginning of the Eocene. Two primate superfamilies, Tarsioidea and Adapoidea, dominate early and middle Eocene primate faunas. Warm climates enabled primates to thrive, and warming events within the Eocene facilitated cosmopolitan dispersal. Declining diversity at the end of the Eocene reflects environmental cooling. Fossils of earliest Tarsioidea and Adapoidea are similar dentally, often confused, and appear closely related as stem or crown Haplorhini. The superfamily Tarsioidea is represented by a single genus, Tarsius, living today, while Adapoidea appear to be ancestral to living Anthropoidea. Little is known of the Eocene history of strepsirrhine Lemuroidea and Lorisoidea. Temporal scaling of molecular clock ages suggests that Strepsirrhini appeared before Haplorhini in the Paleocene or possibly with Haplorhini at the beginning of the Eocene. Substantial skeletons of Eocene primates like those of adapoid Darwinius and Europolemur from Messel in Germany and Notharctus and Smilodectes from western North America constrain phylogenetic interpretation of primate relationships much more than dental remains ever can. A specialised grasping foot distinguishes early primates from other mammals. Traits associated in a functional complex include replacement of claws by nails on all digits; movement of the pedal fulcrum from the metatarsals to the tarsals; elongation of digit IV relative to digit III, with reduction of digit II and sometimes III; and then secondary development of a grooming claw or claws on digits II and sometimes III. The specialised grasping foot of early primates was later moderated in the emergence of anthropoid primates.

Abstract: Eocene mammals from Grube Messel are divided into those that lived terrestrially on the ground (2D-mammals) or arboreally (3D-mammals). Their biomechanics and locomotion are discussed on the basis of equids (Eurohippus, Propalaeotherium) and Leptictidium as examples of 2D-mammals and primates (Europolemur, Darwinius) of 3D-mammals. The determining factor for lifestyle is the autopodia: 2D-mammals need nothing more than compression-transmitting balls with reinforced anterior margins (hooves). These autopodia do not require much energy, but metapodia and even phalanges can elongate the functional length of the free limbs. Primates as 3D-animals need prehensile hands and feet, which can transmit tensile forces and even torques. Their metapodials are part of the prehensile organ. Their strong and energy-requiring musculature increases the masses on the distal limb segments and so influences the locomotor modes.

Abstract: The comparative method is central to interpretations of Eocene primate palaeobiology. This method rests upon a thorough study of analogous living forms. With a rapidly increasing knowledge of such forms, most notably the Malagasy lemurs, our ability to advance the study of Eocene primate ecology, biology and behaviour far exceeds that of even just a few years ago. Here we present such a comparison. Based on our data collected from both living lemurs and extant lemur skeletal specimens, we are able to make a number of comparisons that provide insight into middle Eocene primate ecology and palaeobiology. At the Beza Mahafaly Special Reserve, Madagascar, omnivorous living ring-tailed lemurs that feed on large, hard and tough fruits display a pattern of frequent post-canine tooth wear laterality (62 %) when compared to sympatric, folivorous Verreaux’s sifaka (4 %). Our results indicate that Notharctus does not display a high frequency of tooth wear laterality (7 %), indicating folivory without processing large, hard fruits with its postcanines. Our data on Notharctus tooth wear also indicate, similar to living ring-tailed lemurs at Beza Mahafaly, that numerous individuals (21 %) survived long enough to experience heavy tooth wear, contrary to the assumption that heavy tooth wear leads to the rapid death of the individual. Finally, our data on trauma and injury from a living lemur population suggest that the reported wrist injury in Darwinius masillae (i.e. “Ida”) did not necessarily lead to her death, as numerous ring-tailed lemurs at Beza Mahafaly survive with similar or even more traumatic injuries and maintain the ability to climb. Thus, our data from living primates provide a broad comparative framework for interpreting the ecology, biology and behaviour of Eocene forms.

Abstract: In May 2009, a new fossil entered the history books: "Ida", a.k.a. Darwinius masillae, the most complete fossil primate ever found (Franzen et al. 2009). All around the world, from secluded palaeontology laboratories to the mass-frequented internet, this little female had tongues wagging vehemently about our own origin. Indeed, whereas everybody agrees that "Ida" belongs to the adapiforms (an extinct group of primates traditionally allied with lemurs), Franzen et al. (2009) claim that, based on features displayed by "Ida", the whole Adapiform clade should be allied with Haplorhini (tarsiiforms, monkeys and apes). Detractors of this hypothesis would question the significance of the characters chosen by Franzen et al. (2009), or even their interpretation, and put forth other morphological characters as well as other fossil primates as arguments against a relationship between haplorhines and adapiforms. Determinedly, these critics argue that more features support the widely held hypothesis that adapiforms and lemurs (Lemuriformes) are sister taxa in the clade Strepsirrhini. In any case, "Ida" is a wonderful fossil, which also advertises—thanks to her name “masillae”—the site of Messel that bore her remains for over 47 million years. Masilla is the Latin name for Messel used in the Lorsch monastery Codex, 800 AD. ... Messel, ...