New fossils of Giraffoidea (Mammalia: Artiodactyla) from the Lothidok Formation (Kalodirr Member, Early Miocene, West Turkana, Kenya) contribute to our understanding of early giraffoid diversity

Excavations at Kalodirr and Moruorot from the Lothidok Formation (ca. 17 mya) in the West Turkana Region of Kenya have yielded several cranial appendages, dentitions and postcranial fossils that can be attributed to either Climacoceratidae or the Giraffidae. An additional unusual and unique fossil, we describe in this paper for the first time, is, in our opinion, a novel stem-giraffoid cranial appendage. The Climacoceras from Kalodirr is the oldest representative of the genus, extending Climacoceratidae into the Early Miocene. We establish that by the end of the Early Miocene in Africa the Giraffoidea included at least two families, Climacoceratidae and Giraffidae, distinguished by different types of cranial appendages. Furthermore, the Giraffidae include at least two distinct lineages, represented by distinctive ossicones found at Kalodirr and Moruorot. Thus, we recognize that unlike at older sites where only Canthumeryx is recognized, by the later part of the early Miocene, Giraffoidea communities in East Africa include as many as three genera, and perhaps even four. This pattern of diversity in giraffoid communities persisted into the Middle Miocene and beyond

New fossils of Giraffoidea (Mammalia: Artiodactyla) from the Lothidok Formation (Kalodirr Member, Early Miocene, West Turkana, Kenya) contribute to our understanding of early giraffoid diversity

Excavations at Kalodirr and Moruorot from the Lothidok Formation (ca. 17 mya) in the West Turkana Region of Kenya have yielded several cranial appendages, dentitions and postcranial fossils that can be attributed to either Climacoceratidae or the Giraffidae. An additional unusual and unique fossil, we describe in this paper for the first time, is, in our opinion, a novel stem-giraffoid cranial appendage. The Climacoceras from Kalodirr is the oldest representative of the genus, extending Climacoceratidae into the Early Miocene. We establish that by the end of the Early Miocene in Africa the Giraffoidea included at least two families, Climacoceratidae and Giraffidae, distinguished by different types of cranial appendages. Furthermore, the Giraffidae include at least two distinct lineages, represented by distinctive ossicones found at Kalodirr and Moruorot. Thus, we recognize that unlike at older sites where only Canthumeryx is recognized, by the later part of the early Miocene, Giraffoidea communities in East Africa include as many as three genera, and perhaps even four. This pattern of diversity in giraffoid communities persisted into the Middle Miocene and beyond

Evolution of the Aeluroid Camivora: Hyaenid Affinities of the Miocene Camivoran Tungurictis spocki from Inner Mongolia

Among the mammalian fossils discovered in were crania and mandibles of rare carnivorans, 1930 by the Central Asiatic Expedition of the including the first complete skulls of several Asian American Museum of Natural History (New York) mid-Miocene lineages. Most of these fossils came in the Tung Gur Formation of Inner Mongolia from a single locality termed Wolf Camp Quarry that produced, among other striking finds, a small fox-sized cranium referred to a new genus and species Tungurictis spocki Colbert 1939. Today this remains the only known cranium of Tungurictis yet discovered. Preparation and reinterpretation of the auditory region demonstrate that Tungurictis belongs to an early lineage of Hyaenidae, although it has long been regarded as a viverrid. The WolfCamp Quarry cranium of Tungurictis combines a hyaenid auditory bulla structure with incipient hyaenid specializations of the cheek teeth, indicating that the typical bulla pattern evolved prior to the robust, bone-crushing dentitions that characterize living species of Crocuta and Hyaena. Previously undescribed remains of left and right hindfeet found in Wolf Camp Quarry near the skull are attributed to the same species, if not the same individual, and indicate that a digitigrade paraxonic stance characterized this small Asian carnivore. Tungurictis has been identified only in the Tung Gur Formation of Mongolia, with the exception of a doubtfully referred upper jaw fragment from north Africa. However, a survey of dentitions of small mid-Miocene European hyaenids indicates that the cheek teeth of Tungurictis spocki are comparable to the holotype dentition of Protictitherium gaillardi (Forsyth-Major, 1903) from the mid- Miocene of La Grive, France. So similar is the dental morphology that hyaenid basicranial structure can be reasonably inferred for P. gaillardi, and for Protictitherium for which no basicranium was known. Thus, at least three lineages of small hyaenids with plesiomorphic dentitions (lacking durophagous specializations of the premolars and carnassials) lived in Eurasia during the Miocene: (1) a Protictitherium (Tungurictis) lineage, with hypercarnivorous dentition and hyaenid auditory region; (2) a Protictitherium (Protictitherium) lineage, known chiefly from dentitions in which the ml entoconid is emphasized-an intact auditory region is not yet identified; (3) a Plioviverrops lineage, with hypocarnivorous dentition and hyaenid auditory region. Two additional early hyaenid lineages (Miohyaena, Percrocuta) of the mid-Miocene cannot be confused with Protictitherium or Plioviverrops because they show a precocious development of durophagous dental specializations, heralding the large bone-crushing species of the later Cenozoic of Eurasia. Old World Miocene hyaenids parallel New World Miocene canids in body size, skull form, dental specialization, and diversity. Small, intermediate, and large-sized digitigrade canid and hyaenid ecomorphs are known during the Neogene, some with plesiomorphic skull form and dentition, others with derived hyaenoid cranium and teeth, including durophagous animals of large body size within both Hyaenidae (Dinocrocuta, Pachycrocuta, Adcrocuta) and Canidae (Epicyon, Borophagus, Osteoborus)

Dead ossicones, and other characters describing Palaeotraginae (Giraffidae; Mammalia) based on new material from Gansu, Central China

While the identity and validity of the extant families of ruminants are undoubted, there are significant problems with the determination of the interrelationships among the families, notably within the families of the Pecora, or horned ruminants. The morphological features used to construct ruminant phylogeny have been a source of controversy: many features used over the past century have been shown to be highly homoplastic and related to functional similarities. Ruminants evolved in the context of the later Cenozoic climatic changes, and many lineages adopted functional morphological adaptations related to feeding on more abrasive diets (resulting in the parallel evolution of a greater extent of loph development in the molars and, in some lineages, hypsodonty) and locomotion in open habitats (resulting in the parallel evolution of fused metapodials and reduction and/or loss of lateral digits). The fact that the molecular phylogeny shows a very different pattern from the currently accepted morphological one is of particular cause for concern, especially as molecular data are of no use for understanding the relationships of extinct lineages. Here we review the morphological data used in ruminant phylogenetics, and show even many of the less obviously functional features (e.g., number and position of the lacrimal orifices) are subject to homoplasy and variation, especially when fossil taxa are included. In addition, many morphological features treated as independent traits in phylogenetics are correlated (e.g., cranial morphology associated with hypsodonty). Some potentially reliable features are identified, but these do not help to sort out relationships within the Pecora. We advocate for the investigation into better morphological features, possibly derived from basicranial and ear region characters (although these features are not without their own issues of homoplasy), and for caution in character consideration in performing phylogenetic analyses

The extinct, giant giraffid Sivatherium giganteum: skeletal reconstruction and body mass estimation

Sivatherium giganteum is an extinct giraffid from the Plio–Pleistocene boundary of the Himalayan foothills. To date, there has been no rigorous skeletal reconstruction of this unusual mammal. Historical and contemporary accounts anecdotally state that Sivatherium rivalled the African elephant in terms of its body mass, but this statement has never been tested. Here, we present a three-dimensional composite skeletal reconstruction and calculate a representative body mass estimate for this species using a volumetric method. We find that the estimated adult body mass of 1246 kg (857—1812 kg range) does not approach that of an African elephant, but confirms that Sivatherium was certainly a large giraffid, and may have been the largest ruminant mammal that has ever existed. We contrast this volumetric estimate with a bivariate scaling estimate derived from Sivatherium's humeral circumference and find that there is a discrepancy between the two. The difference implies that the humeral circumference of Sivatherium is greater than expected for an animal of this size, and we speculate this may be linked to a cranial shift in centre of mass

Hypsodont Crowns as Additional Roots: A New Explanation for Hypsodonty

The hypsodont crown of Equus and of other hypsodont ungulates has two functions: It has an extra crown in the alveolus which erupts and becomes a functional crown that enables the horse to live longer and feed on abrasive foods and grit. The second functional aspect is that the crown, while it is in the alveolus, acts as a root to support high stress during mastication. In general, roots do not increase in size during evolution when the tooth crown increases. Delayed development of the true root is a heterochrony phenomenon and is possibly dynamically interactive with the forces applied on the crown. Thus, when the crown becomes worn, as in old age, the mastication forces acting on it are very strong. This is an interesting phenomenon and reinforces our hypothesis of the second functional difference that the young tooth's crown embedded in the alveolus acts as a supporting root. The Equus hypsodont tooth has been represented by a class I lever. That is, the fulcrum is in the middle: the effort is applied on one side of the fulcrum and the resistance (or load) on the other side, for example, as in a crowbar. As an individual Equus ages, the alveolar tooth height decreases. Data display an exponential increase in force generated as tooth height decreases. The elongation and closure of the root is delayed until the crown is almost entirely worn. When the crown becomes worn, the mastication forces acting on it are very strong. This is an interesting phenomenon and reinforces our hypothesis that the young tooth's crown, embedded in the alveolus, acts as a supporting root. This discovery is based on the observation that fossil ungulates most commonly die at an early age, leaving a substantial amount of crown unused. The unused crown is not likely a reserve tooth crown for a season of hardship because it is rare to find examples of such hardships in the fossil record

Ungulate molars

36 p. : ill. ; 26 cm.Includes bibliographical references (p. 33-35).The analysis of fossil ungulate cheek teeth has long been one of the main sources of information about the terrestrial environments of the Cenozoic, but the methods used to extract this information have been either imprecise or prohibitively laborious. Here we present a method based on relative facet development that is quantitative, robust, and rapid. This method, which we term mesowear analysis, is based on the physical properties of ungulate foods as reflected in the relative amounts of attritive and abrasive wear that they cause on the dental enamel of the occlusal surfaces. Mesowear was recorded by examining the buccal apices of molar tooth cusps. Apices were characterized as sharp, rounded, or blunt, and the valleys between them either high or low. The method has been developed only for selenodont and trilophodont molars, but the principle is readily extendable to other crown types. Mesowear analysis is insensitive to wear stage as long as the very early and very late stages are excluded. Cluster analysis of the mesowear variables produces clusters reflecting four main groups from abrasion-dominated to attrition-dominated: grazers, graze-dominated mixed feeders, browse-dominated mixed feeders, and browsers. Most of the relatively few apparent anomalies are explained by more detailed dietary information. Mesowear analysis provides resolution within the main dietary classes and the clustering is virtually identical with and without the index of hypsodonty. Discriminant analysis using all mesowear variables and hypsodonty showed an overall correct classification of 76% of 64 species of living ungulates into the conventional dietary categories of browser, grazer, and mixed feeder, while a smaller set of 27 "typical" species was correctly classified at 96%. Alternative "conservative" and "radical" dietary classifications that were employed to accommodate cases where dietary information was controversial or unclear produced only marginally different results. Mesowear analysis successfully resolved a test case using the Serengeti grazing succession and appears to be superior to microwear analysis in two cases where the diet of fossil ungulates has been previously studied by microwear and other conventional methods