Cave bears, an extinct subgenus (Spelearctos) of Ursus, were versatile enough to inhabit large areas of the northern hemisphere during the middle and late Pleistocene, yet they had evolved a specialized dentition that emphasized grinding functions, implying a heavy dietary reliance on tough, fibrous foods (i.e., plants). Isotope studies have yielded conflicting results on cave bear diet, however, often without consideration of the provenance of the samples or the possible contradictions that taphonomic and morphologic evidence might pose to dietary interpretations. It is likely that cave bear habits varied somewhat in response to environmental circumstance, and the limits on their abilities to do so remain unknown. If the larger goal of paleontological inquiry is to reconstruct the adaptations of cave bear species, then variation and commonalities among populations must be tracked closely, and the disparate lines of evidence currently available examined together on a case by case basis. Clearly, no single analytical technique can achieve this. By way of example we present the results of a cross-disciplinary collaboration that combines osteometric, isotopic, and taphonomic approaches to studying the paleoecology of a bear assemblage from Yarimburgaz Cave in northwest Turkey. Reference information on the linkages between diet, hibernation, and population structure in modern bears provides test implications for the investigation. Osteometric techniques demonstrate the presence of two coextant middle Pleistocene bear species in the sample–Ursus (Spelearctos) deningeri, a form of cave bear, and U. arctos or brown bear–the former abundant in the sample, the latter rare. An attritional mortality pattern for the bears and the condition of their bones show that most or all of the animals died in the cave from nonviolent causes in the context of hibernation. The study also elucidates several characteristics of the cave bear population in this region. Osteometric techniques show that the adult sex ratio of the cave bears is only slightly skewed toward females. This pattern lies near one extreme of the full range of possible outcomes in modern bear species and can only reflect a strong dietary dependence on seasonally available plants and invertebrates, showing that hibernation was a crucial overwintering strategy for both sexes; the results specifically contradict the possibility of regular, heavy emphasis on large game (hunted or scavenged) as a winter food source. The nature of wear and breakage to the adult cave bear teeth indicates that food frequently was obtained from cryptic sources, requiring digging and prying, and that extensive mastication was necessary, leading to complete obliteration of some cheek tooth crowns in old individuals. The patterns of tooth damage during life corroborate the dietary implications of the adult sex ratio and also argue for a diet rich in tough, abrasive materials such as nuts, tubers, and associated grit. The carbon and oxygen isotopic compositions of cave and brown bear tooth enamel from the site are virtually identical, and there is no evidence of a strong marine signal in either species, despite the cave's proximity to a modern estuary of the Sea of Marmara; nitrogen isotope ratios could not be examined because of poor protein preservation. The isotope results suggest that both bear species were highly omnivorous in the region during the middle Pleistocene and obtained nearly all of their food from terrestrial and fresh-water habitats. Bone pathologies, usually originating from trauma, occur in some of the adult bears, testifying to long lifespans of some individuals in this fossil population. The Yarimburgaz cave bears also exhibit great size dimorphism between the sexes, based on weight-bearing carpal bone dimensions, with adult males attaining roughly twice the body mass of adult females.

The eutatines are a group of fossil armadillos traditionally regarded as herbivorous due to the particular morphology of the skull and teeth. Nevertheless, they have never been the subject of a detailed morpho-functional analysis. The masticatory apparatus of Eutatus (late Pliocene–early Holocene) is analyzed and compared with other eutatines (Proeutatus and Stenotatus from the Miocene, and Doellotatus and Ringueletia from the Pliocene) and with living armadillos (Euphractus and Dasypus). The masticatory muscles were reconstructed from origin and insertion scars; the occlusal pattern and mandibular movements were determined through the study of the craniomandibular joint, the shape and arrangement of the teeth and the symphysis, and the moment arms of the lines of action of the masseter and temporalis muscles were estimated. Skull and mandible shapes were compared using the Procrustean method Resistant-Fit Theta-Rho-Analysis (RFTRA). The analysis of the masticatory apparatus of the eutatines allows us to state that Eutatus and Proeutatus exhibit the most specialized morphology known for an herbivore with an armadillo-like skull pattern. Additionally, we can identify a morphological group from the Miocene Stenotatus to the Pleistocene Eutatus, including the Pliocene Doellotatus and Ringueletia as intermediate stages of a morphological line; Proeutatus deviates from this pattern. This morphological separation may reflect an early dichotomy within the well-defined clade of eutatines.

Evidence that can be used to interpret the life habits of extinct organisms usually takes three forms: functional analysis, analogy with living organisms, and geological evidence. Independent quantitative tests for habit are rarely available. A theory of optimum eye design originally derived for living aquatic arthropods provides quantitative data that are used to test previous suppositions about the life habits of two Ordovician pelagic trilobites: that the telephinid trilobite Carolinites was epipelagic while the cyclopygid Pricyclopyge was mesopelagic. Optimum compound eye design theory uses measured lens diameters and interommatidial angles to determine the “eye parameter” (p), which can be used to gauge approximate optimum level of illumination for the eyes of these trilobites. The eye parameter provides an independent test for their relative paleobathymetry. Values of the eye parameter measured in the dorso-ventral direction across two eyes of Carolinites killaryensis utahensis were found to have medians of 2.13 and 3.24. Values measured in the antero-posterior direction have medians of 3.17 and 4.86 for the two eyes. Values measured in the dorso-ventral direction across two eyes of Pricyclopyge binodosa have medians of 4.23 and 4.98, while values measured in the antero-posterior direction have medians of 7.06 and 8.31. Eye parameters are higher in Pricyclopyge than in Carolinites, the difference statistically significant at p = 0.05. The eyes of Pricyclopyge are optimally designed for lower levels of illumination than are those of Carolinites. This accords with the previous interpretations of the former trilobite as mesopelagic and the latter as epipelagic.

Ecotypic correlations between stable isotopic signals and skeletal size indicate that some Late Cretaceous serial planktic foraminifera were strongly photosymbiotic. In contrast, coeval trochospiral planktic foraminifera do not exhibit the isotope/size signatures that typify strongly photosymbiotic species. Comparison to Cenozoic taxa demonstrates that photosymbiosis has recurred throughout planktic foraminiferal history and has evolved independently in superfamilies characterized by very different gross skeletal morphologies. The historical contingency of that evolution is illustrated by the consequences of the Cretaceous/Paleogene mass extinction, which terminated the Cretaceous lineages of photosymbiotic planktic foraminifera but did not permanently extinguish photosymbiont reliance by planktic foraminifera.

The origin of mammals has been characterized as a gradual process, a claim based primarily on a well-preserved series of extinct nonmammalian synapsids (“mammal-like reptiles”) that span some 200 million years. In contrast to the origin of many other higher taxa, the origin of mammals from within cynodont-grade therapsids is not considered to coincide with a major morphological change, but rather to be simply the culmination of a series of more and more mammal-like transitional forms. To test these assertions, an asymmetrical cladogram extending from primitive “pelycosaurs” to morganucodontid mammaliaforms was created. Three different methodologies were then used to compare the amount of morphological change between nodes on this cladogram with the minimum missing time interval between each node, as inferred from sister taxon-based ghost lineages. In general, a statistically significant positive relationship was found, indicating that greater numbers of derived features tend to be correlated with longer ghost lineages. A significant correlation between the number of accumulated apomorphies and branching events was also found. Although the rate of character change was variable, in no case was a long ghost lineage associated with few apomorphies. These correlations are consistent with the hypothesis that rapid accumulation of derived features occurred relatively infrequently within the synapsid lineage leading toward mammals and that gradual character evolution predominated.

Synchronous episodes of phenotypic change in five lineages of the endemic land snail genus Mandarina of the oceanic Bonin (Ogasawara) Islands through 40,000 years were documented by morphological analyses of radiocarbon-dated fossil specimens. Adult shell traits of these lineages show mostly synchronous patterns of change with longer intervals of stability and rapid shifts to other states of stability. Although there are intermediates between these different phenotypic states, the net interval of the phenotypic shift was relatively short, i.e., no longer than 7000 years. Extinction of a lineage and speciation occurred during the intervals of the rapid phenotypic shift. This period of abrupt change corresponds to the period of lowest sea level and end of the last glacial period. This implies that climatic change is one of the causes of these episodes of simultaneous rapid phenotypic shifts, speciation, and extinction in different lineages. These findings suggest that major phenotypic changes in phyletic evolution, separation of different species, and extinction of lineages may occur synchronously in many lineages during an extremely short interval.

Evolutionary paleoecology is the study of paleoecological patterns of organization over time. However, identification of such patterns within modern communities must be made before any study over time can be attempted. This research analyzes mammalian ecological diversity of 31 African localities classified into eight vegetation types: forests, closed woodlands, closed woodland/bushland transition, bushlands, open woodlands, shrublands, grasslands, and deserts. Ecological diversity is measured as the relative proportions of large mammal trophic and locomotor behaviors within communities. Trophic and locomotor adaptations are assigned on the basis of published observations and stomach contents of 184 African mammal species. Communities are accordingly described on the basis of total percentages of mammalian trophic and locomotor adaptations. Since many paleoecology studies have been made using taxonomic uniformitarianism, this study also examines taxonomic community structure to compare with ecologically derived patterns.

Results indicate that particular types of vegetation have predictable percentages of arboreal, aquatic, frugivorous, grazing, etc. large mammals. Therefore, these adaptations, because they are predictable in extant assemblages, can be used to predict paleovegetation as well as to portray the community structure of fossil assemblages. Taxonomic groupings also can be used to predict vegetation in extant assemblages, and taxonomic patterns in communities are compared with ecological ones.

The mammalian communities of the Pliocene fossil locality Makapansgat, South Africa, are interpreted using these ecological and taxonomic methodologies. Trophic and locomotor adaptations are assigned for Makapansgat fossil mammals through morphological examination of each taxon. Vegetation type is predicted for these fossil localities, but ecological and taxonomic differences in the assemblages differ from extant communities.

Gastropod opercula are classified here on a new morphogenetic basis, which distinguishes three main types: (1) flexiclaudent spiral (mostly multispiral) operculum, the shape of which does not coincide with that of the aperture, (2) rigiclaudent spiral (usually paucispiral) operculum, the shape of which fits that of the aperture, and (3) rigiclaudent concentric operculum, also aperture-fitting. The first type fits by flexing into the aperture and is secreted when the soft parts are partly or wholly extended (i.e., when the operculum is not in a closed position). The other two types do not flex upon retraction (except at the very margin) and grow when the operculum closes over the aperture, with or without rotation. A study of opercular types at the family level confirms the systematic and evolutionary significance of opercula. Types 1 and 2 are the only ones present in archaeogastropods, Type 1 being predominant. Opercula (if present) in Neritopsina are always rigiclaudent. Within Caenogastropoda, Type 2 predominates; the only flexiclaudent spiral opercula are found in certain basal cerithioidean families. Concentric opercula are predominant in higher neotaenioglossans and exclusive in neogastropods. Except for one family, opercula in Heterostropha are always rigiclaudent spiral. Morphological, systematic, and histological criteria point to the flexiclaudent spiral operculum as the ancestral form. This leads us to propose the “periostracum shaving” model in prosobranchs to account for the origin of this kind of operculum. According to this model, in the earliest trochospiral gastropods the periostracum ceased to serve a shell-formation function at the band of overlap between whorls (the parietal band). The periostracal band was then extruded from the shell to constitute an incipient operculum, taking on the appearance of a spiral strip coiling opposite to the shell. The parietal segment of the periostracal groove migrated toward the epipodium and became independent from the rest of the mantle. The concomitant development of an opercular disc allowed the successive turns of periostracal strip to seal together. In this way, a spiral operculum emerged, coiling counterclockwise without matching the aperture shape. During the course of prosobranch evolution, rigiclaudent spiral opercula emerged several times from the ancestral flexiclaudent type, although they were always restricted to apertures with a spiral-shaped outer (labral) edge. Such opercula enlarged the range of shell morphologies for which the operculum constituted an efficient protective barrier to include those of neritoidean or naticoidean type. The onset of calcification in opercula took place with the rigiclaudent type. Concentric opercula also evolved independently from rigiclaudent spiral opercula in several gastropod groups, thus further broadening the spectrum of apertures and, hence, of shell morphologies using opercula for protection. From the standpoint of adaptation, the concentric type was probably the only one available to neogastropods having long and wide siphonal canals.

Carbon (δ13C) and oxygen (δ18O) isotopic results are presented from 42 tooth enamel carbonate samples of rhinos (Family Rhinocerotidae) from a sequence of Florida Neogene localities between 9.5 and 4.5 Ma. These data are used to interpret ancient diets and test previous hypotheses of terrestrial/aquatic adaptations of two sympatric rhinos, Aphelops and Teleoceras. The long-limbed, shorter-crowned Aphelops traditionally has been reconstructed as an open-country browser (similar to the modern black rhino), whereas short-limbed, higher-crowned Teleoceras traditionally has been reconstructed as an amphibious grazer (similar to the modern hippo). Between about 9. 5 and 7 Ma the δ13C values (all <−11.0‰) from Florida Aphelops and Teleoceras indicate that both rhinos were feeding on C3 plants. This diet probably included a combination of browse and C3 grasses, although the exact proportions for each genus cannot be distinguished isotopically. In contrast, after the late Miocene global carbon shift as represented at 4.5 Ma in Florida, Aphelops was a browser (mean δ13C = −11.9‰), whereas Teleoceras was a mixed feeder/C4 grazer (mean δ13C = −7.0‰). Oxygen isotopic values indicate that neither Aphelops nor Teleoceras was principally aquatic. Given these new isotopic data, more plausible modern analogs for these two extinct rhinos are, respectively, the terrestrial browsing black rhino (Diceros bicornis) and the terrestrial grazing white rhino (Ceratotherium simum), which are sympatric today in Africa.

The shells of gastropods and cephalopods grow by production of new material, by the mantle, at the lip of the shell. I derive a model of shell form that allows us to describe the morphology of a shell in terms of independently definable biological parameters. These are (1) the relative rates of shell production at different points around the aperture, (2) the total amount of shell produced per time interval, (3) the growth rate of the aperture, (4) aperture shape, and (5) the orientation of the animal within the shell. Describing shell form in these terms allows us to see what biological changes must occur in development in order to change one shell morphology into another and what constraints are associated with particular morphological transformations. The model shows that it is developmentally easy to derive a slightly coiled limpet shell from that of a high-spired ancestor, but difficult to take the next step to a fully conical limpet. Many, if not most, real gastropod shells are not conical but rather have a convex or concave profile. I show that these forms result from a decoupling of shell production rates from the growth rate of the animal within the shell. The model also shows how truly different forms, such as vermetid snails and heteromorph ammonites, escaped the confines of spiral growth–sometimes by rotating the body within the shell, and sometimes by taking up a growth strategy that does not constrain them to coil. This model is compatible with shell morphometric models that have been widely discussed in the literature but strives toward a different goal: understanding the relationships between the various biological processes involved in shell development.