Comparative bite forces and canine bending strength in feline and sabretooth felids: implications for predatory ecology

The sabretooth felids were widespread across much of the world in the Late Tertiary, and appear to have been an important group of large predators. Owing to the substantially different skull morphology of derived sabretooths compared with extant felids, there has been considerable debate over the killing mode, bite forces, and bending strength of the large upper canines, and over the implications of these characteristics on feeding ecology. Debates have, however, usually been based on indirect comparisons of force vectors. In this paper, I provide assessments of the estimated force output from the jaw adductor muscles, based on estimates of muscle cross-sectional areas and force vectors, along with canine bending strengths, in a variety of sabretooth felids, in comparison with extant felids. In general, sabretoothed felids had moderately powerful bites, albeit with less jaw adductor power for their body sizes compared with extant felids, sometimes markedly so. Less derived sabrecats appear to have had proportionally higher bite forces than derived forms. The length of the upper canines seemingly compromised their bending strength at any given body size, and again this was most marked in derived forms. However, compared with estimated jaw adductor forces, the canines of sabrecats appear, if anything, to have been stronger than those of extant conical-toothed felids. It has previously been suggested that large sabretoothed felids hunted large prey with a canine shearing bite, powered in part by the jaw adductors and in part by the muscles of the upper neck–occipital region. The present results of canine bending strengths versus the predicted bite force from the jaw adductors supports this suggestion.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 151 , 423–437.     

The making of a monster: postnatal ontogenetic changes in craniomandibular shape in the great sabercat Smilodon

Derived sabercats had craniomandibular morphologies that in many respects were highly different from those of extant felids, and this has often been interpreted functionally as adaptations for predation at extreme gape angles with hypertrophied upper canines. It is unknown how much of this was a result of intraspecific postnatal ontogeny, since juveniles of sabercats are rare and no quantitative study has been made of craniomandibular ontogeny. Postnatal ontogenetic craniomandibular shape changes in two morphologically derived sabercats, Smilodon fatalis and S. populator, were analysed using geometric morphometrics and compared to three species of extant pantherines, the jaguar, tiger, and Sunda clouded leopard. Ontogenetic shape changes in Smilodon usually involved the same areas of the cranium and mandible as in extant pantherines, and large-scale modularization was similar, suggesting that such may have been the case for all felids, since it followed the same trends previously observed in other mammals. However, in other respects Smilodon differed from extant pantherines. Their crania underwent much greater and more localised ontogenetic shape changes than did the mandibles, whereas crania and mandibles of extant pantherines underwent smaller, fewer and less localised shape changes. Ontogenetic shape changes in the two species of Smilodon are largely similar, but differences are also present, notably those which may be tied to the presence of larger upper canines in S. populator. Several of the specialized cranial characters differentiating adult Smilodon from extant felids in a functional context, which are usually regarded as evolutionary adaptations for achieving high gape angles, are ontogenetic, and in several instances ontogeny appears to recapitulate phylogeny to some extent. No such ontogenetic evolutionary adaptive changes were found in the extant pantherines. Evolution in morphologically derived sabercats involved greater cranial ontogenetic changes than among extant felids, resulting in greatly modified adult craniomandibular morphologies.     

A dynamic model for the evolution of sabrecat predatory bite mechanics

The ability of sabretoothed felids to achieve sufficiently high bite forces for predation at extreme gape angles has been the subject of decades of debate. Previous studies have indicated that bite forces in derived sabretoothed felids would have been low, but that they were probably augmented by head depressing muscles. However, bite mechanics is a dynamic process, and mechanical properties change with changes in gape angles. In this study, I present the first comprehensive model of bite mechanics, vector angles, and forces about the temporomandibular joint at gape angles from occlusion to maximal inferred gape in sabretoothed felids. Primitive sabrecats (Machairodus, Paramachairodus) appear broadly comparable to extant large felids (Panthera, Puma), but derived sabrecats in the groups Homotherini (Amphimachairodus, Homotherium, Xenosmilus) and Smilodontini (Megantereon, Smilodon) are often substantially different from either of the former. The ability of the mandibular adductors to generate torque changes with gape angle, indicating that previous models fail to capture potentially important differences in bite function. Inferred muscle sizes and the angles of effective torque from individual adductor fibres in derived sabrecats are different from those of primitive sabrecats and extant large felids, but they had evolved a number of compensatory adaptations for maximizing force output at the canine and carnassial, primarily changes in muscle fibre angles and more compact crania. Inferred outforces at the canines and carnassials were comparable amongst all groups at low gape angles, but at extreme gape angles outforces would have been low, supporting previous hypotheses of head flexor contribution during initial stages of the killing bite in sabrecats. Mandibular adduction in extant carnivores is a complicated pattern of differences in twitch tension and electromyographical activity at different gape angles, and inference of maximal isotonic bite forces from reconstructed mandibular adductor sizes in fossils will give estimates primarily suitable for comparative purposes. Potentially, derived sabrecats could have evolved differences from extant felids in adductor histochemistry or pinnation angle of individual fibres. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162 , 220–242.     

Functional morphology of neck musculature in the Tyrannosauridae (Dinosauria, Theropoda) as determined via a hierarchical inferential approach

With multiple well-preserved specimens, tyrannosaurid dinosaurs are ideal subjects for exploring the role of the neck for feeding in an extinct amniote clade. Detailed exploration of the morphology of avian and crocodilian neck muscles grounds phylogenetic inference of musculature of tyrannosaurids. Introduced methods of kinematic and physiological inference explicate action and function of tyrannosaurid neck muscles, and the explicit method of extant behavioural interpolation (EBI) allows inference of generalized behaviours. Anteriorly originating craniocervical muscles of tyrannosaurids, and insertions of the neck dorsiflexor m. transversospinalis cervicis, were similar to those of birds, while the major respective head dorsiflexor and lateroflexor, m. transversospinalis capitis and m. longissimus capitis superficialis, resembled their homologues in crocodilians. Because the proposed inferential methods are cumulative and emphasize mutual falsification, behavioural effects of muscle function become immediately testable rather than assumed. Kinematic inference of muscle moment topology, and bracketed and unipolar inference of muscle activity, facilitate EBI of rapid gaze shifts, lateral and sagittal strikes, inertial feeding, and tearing of flesh by specific permutational actions of tyrannosaurid neck muscles. Several examples of EBI are tested further through biomechanical considerations.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 151 , 759–808.     

An integrative phylogenetic and extrapolatory approach to the reconstruction of dromaeosaur (Theropoda: Eumaniraptora) shoulder musculature

Dromaeosauridae is the sister taxon of the Avialae; thus, an investigation of dromaeosaur shoulder girdle musculature and forelimb function provides substantial information regarding changes in the size and performance of the theropod shoulder girdle musculature leading to avian powered flight. Twenty-two shoulder girdle muscles were reconstructed for the dromaeosaurid shoulder apparatus, based on phylogenetic inference, which involves the comparison of lepidosaurian, crocodilian and avian musculature, and extrapolatory inference, which involves a secondary comparison with functional analogues of theropods. In addition to these comparative methodologies, osteological correlates of shoulder musculature preserved in eumaniraptorans are identified, and comparisons with those of extant archosaurs allow these muscles to be definitively inferred in dromaeosaurids. This muscle reconstruction provides a foundation for subsequent investigation of differences in muscular attachment and function, based on scapulocoracoid morphology, across the theropod lineage leading to birds.  © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 146 , 301–344.     

Osteology and ecology of Megantereon cultridens SE311 (Mammalia; Felidae; Machairodontinae), a sabrecat from the Late Pliocene – Early Pleistocene of Senéze, France

Megantereon cultridens was a derived, Late Pliocene to Early Pleistocene sabrecat, and although fossils of animals referred to the genus and species have been found at several locations throughout Eurasia, most are fragmentary. However, the specimen SE311 from Senéze in France represents an almost complete and well-preserved skeleton, and this is only known from very few other sabrecats, thus providing a rare glimpse into the full anatomy of an unusual and derived sabrecat. In this monograph, we provide a complete overview of the anatomy of Megantereon cultridens SE311, and compare it with extant large felids, and the few other derived sabrecats from which ample fossil material is known, although most frequently representing several specimens. SE311 was a large specimen of M. cultridens and would have had a body mass of 100–110 kg and a head–body length or around 160 cm, which is similar to a small lioness or large male jaguar. Megantereon sp. were sexually dimorphic, and the size of SE311 suggests that it was a male. As with several other derived sabrecats, it was powerfully built, and had particularly robust forequarters with very well-developed muscle attachment sites, indicating a powerful forelimb and shoulder musculature. The neck was proportionally much longer than in extant felids, and the thoracic and particularly lumbar region was proportionally shorter, mimicking the condition in other derived sabrecats from which large parts of the vertebral column is known. Megantereon probably lived in open-forest environments and preyed on cervids, which were dispatched with a shearing bite from the hypertrophied and blade-like upper canines to the throat of the prey, while the prey was held immobile with the massive forelimbs, thus minimizing the risk of damage to the fangs.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 151 , 833–884.     

On the identity of turmeric: the typification of Curcuma longa L. (Zingiberaceae)

Although Curcuma L. (Zingiberaceae) is a conserved name, with C. longa L. as its conserved type, the type of C. longa is still uncertain. Numerous discussions about the identity of the taxon called C. longa by Linnaeus have been followed by various attempts to rename turmeric, suggestions as how to settle the type and proposals to conserve the name from a later author in order to stabilize the situation. Unfortunately, none of the previous proposals can be upheld for reasons which are discussed in this article. A lectotype is selected from extant material examined by Linnaeus and an epitype collected near the type locality is designated here. The identity of C. longa is discussed and a colour plate of the species is included. Synonyms of C. longa and their types are discussed and notes on the variability of C. longa are provided.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 37–46.     

A new species of Prosansanosmilus: implications for the systematic relationships of the family Barbourofelidae new rank (Carnivora, Mammalia)

A new barbourofelid species, Prosansanosmilus eggeri , is described from the Middle Miocene (MN 5) locality of Sandelzhausen, Germany. It differs from all other European barbourofelid species in being smaller and showing a more plesiomorphic morphology, especially in the relatively less developed sabretooth adaptations, low accessory cusps on the premolars, and the remnant of a very small talonid on the carnassial. The species is, however, stratigraphically later than the more apomorphic P. peregrinus, which is known from MN 4 of Germany and France. A phylogenetic analysis based on dental characters of early nimravids, barbourofelids and felids supports previous results on skull morphology of Barbourofelis that Barbourofelinae is not closely related to the Late Eocene and Oligocene Nimravinae. Instead, both subfamilies should be treated as separate families, with the Barbourofelidae closely related to the Felidae. The Barbourofelidae differ from the Felidae as well as from the Nimravidae s.s ., particularly in the unique morphology of their basicranium. They presumably originated in Africa; P. eggeri sp. nov. is interpreted as part of a Miocene immigration of African faunal elements into Europe that took place at the beginning of MN 5. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 140 , 43−61.     

Allozymic differentiation of Tunisian populations of Androctonus species and Buthus occitanus (Scorpiones: Buthidae)

We examined the population structure and phylogeny of Buthus occitanus (Amoreux, 1789), Androctonus amoreuxi (Audouin & Savigny 1812) and Androctonus australis (Linnaeus, 1758) in Tunisia, using horizontal starch gel and polyacrylamide gel electrophoresis to resolve allozymes at 18 loci. Populations of B. occitanus and A. amoreuxi showed little genetic variation, whereas A. australis populations showed moderate genetic variation. Moreover, despite the restricted dispersal abilities of these species, the allozyme analysis indicated very low levels of intraspecific population differentiation. The Island model of population differentiation best fitted the intraspecific variation, both for mainland populations and for the slightly more differentiated populations from two Mediterranean islands. No diagnostic, fixed alleles were observed between the species of Androctonus , which concurs with the results of nuclear ribosomal DNA analysis. Two subspecies of A. australis , A. a. garzonii Goyffon & Lamy, 1973 and A. a. hector Vachon, 1948, were not resolved by a phylogenetic analysis of the allozyme data. The most likely reasons for the slight population differentiation are either low mutation rates or recent range extensions promoted by human activities. The possibility of indirect gene flow between Androctonus species should also be explored.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 255–265.     

Carnivores, biases and Bergmann's rule

Studies of Bergmann's rule may encompass a non-random subsample of extant homeotherms. We examined patterns of correlation between skull length and geographical latitude in 44 species of carnivores in order to test the validity of Bergmann's rule in the Carnivora. Results were then compared to those of other studies. Significant positive correlation between skull length and latitude was found in 50% of carnivore species, while significant negative correlation was found in only 11% of species. These results indicate that the occurrence of Bergmann's rule in the Carnivora is less frequent than earlier published data suggest. Publication bias is not detected in published data. Therefore, previous studies of geographical size variation might be biased in favour of species known to follow Bergmann's rule.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 579–588.     

Body size in proboscideans, with notes on elephant metabolism

Mass estimates for a number of fossil proboscideans were computed using regression analyses on appendicular bones to body mass, for seven specimens of modern elephants, for which body masses had been recorded prior to death. The marked differences in physical proportions between extant Loxodonta and Elephas , implying substantial differences in body mass at any given shoulder height, were not present in their long bone parameters. Length and least circumferences proved to be the best parameters for prediction of body mass. Some extinct proboscideans, notably certain Mammuthus and Deinotherium , were much larger than extant elephants. Both the basal and the field metabolic rates of extant elephants are lower than predicted for a hypothetical mammal, in accordance with their body size and subsistence on low-quality foods. The feeding quantities often ascribed to extant wild elephants are exaggerated, and would in fact have sufficed to nourish much larger species.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 140 , 523–549.     

The old wasp and the tree: fossils, phylogeny and biogeography in the Orussidae (Insecta, Hymenoptera)

The phylogenetic relationships of the fossil orussid taxa Mesorussus taimyrensis and Minyorussus luzzi are examined by analysing them together with a large data set compiled previously for the extant Orussidae. The fossils are placed in an unresolved trichotomy with the extant Orussidae. The phylogeny is used for evaluating the hypothesis that the ancestors of the family had reduced body size; the results of this analysis are inconclusive. The biogeographical history of the Orussidae is explored. The common ancestor of the family was probably widespread, the initial splitting events taking place prior to or coinciding with the separation of Laurasia from Gondwana. Later putative vicariance events can be correlated with the gradual breakup of Gondwana. However, the biogeographical history of the Orussidae is dominated by speciation within regions and dispersal. The minimum age of the common ancestor of the Orussidae is >180 Myr when estimated from the biogeographical pattern, >95 Myr when estimated from the phylogenetic position of the fossils; the earlier date is considered to be the most likely.  © 2004 The Linnean Society of London , Biological Journal of the Linnean Society , 2004, 82 , 139–160.     

Comparative morphology of the dermal palate in squamate reptiles, with comments on phylogenetic implications

The differentiation of the dermal palate and of the septomaxilla in extant squamate reptiles is reviewed in terms of Lakjer's distinctions of a palaeochoanate, incomplete neochoanate, and neochoanate condition. The differentiation of the bones surrounding the mushroom body, Jacobson's organ, and the internal naris (choana) supports a number of clades including Squamata, Scleroglossa, and Autarchoglossa, with Serpentes nested within Autarchoglossa. Dermal palate morphology and the differentiation of the septomaxilla in squamates reflect the evolution of the chemosensory system in general, and the vomeronasal system in particular, and strongly contradict a recent hypothesis of squamate phylogeny based on molecular data.  © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 152 , 131–152.     

Length–weight relationships for 12 fish species caught in Seyhan Dam Lake in southern Anatolia, Adana, Turkey

Presented are the length–weight relationships of 12 fish species [ Oncorhynchus mykiss (Walbaum, 1792); Cyprinus carpio, Linnaeus, 1758; Carassius carassius Linnaeus, 1758; Alburnoides bipunctatus (Bloch, 1782); Alburnus adanensis Battalgazi, 1944; Rutilus rutilus , Linnaeus, 1758; Squalis cephalus, Linnaeus, 1758; Tinca tinca (Linnaeus, 1758); Capoeta barroisi (Valenciennes, 1842); Silurus glanis Linnaeus, 1758; Gambussia affinis (Baird and Girard, 1853); and Sander lucioperca (Linnaeus, 1758)] from Seyhan Dam Lake, Turkey. This study provides the first estimation of length–weight relationships for two of the species ( A.   adanensis and C. barroisi ).     

Cytogenetics of Bolinus brandaris and phylogenetic inferences within the Muricidae (Mollusca: Gastropoda)

The purple dye murex, Bolinus brandaris (Linnaeus, 1758), is a muricid gastropod common throughout the Mediterranean and along the Moroccan and Portuguese Atlantic coasts. In the present study, we confirmed the diploid chromosome number of 2 n  = 70 for this species, and established for the first time the karyotype, which comprised 12 metacentric, 15 submetacentric and eight subtelocentric chromosome pairs. To facilitate cytotaxonomic comparisons, we carried out a comparative karyological analysis through multidimensional scaling between B. brandaris and three other 2 n  = 70 muricid species ( Hexaplex trunculus , Ocenebra erinaceus , and Stramonita haemastoma ) for which chromosomal measurements have been previously published. The interpretation of the ideograms and the statistical analysis highlighted the closest similarity of B. brandaris and H. trunculus compared to S. haemastoma and O. erinaceus . Indeed, B. brandaris and H. trunculus showed the smallest dissimilarities both for relative length and arm ratio, with O. erinaceus presenting intermediate values, whereas the highest dissimilarities were found between H. trunculus and S. haemastoma for both data. The karyotypes of B. brandaris and H. trunculus (subfamily Muricinae) presented the highest proportions of metacentric chromosomes compared to the other two muricids analysed, suggesting that those karyotypes could be considered primitive within the 2 n  = 70 Muricidae studied so far.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 185–193.     

Phylogeny of the great cats (Felidae: Pantherinae), and the influence of fossil taxa and missing characters

Molecular phylogenetic studies of the extant Pantherinae have resulted in a variety of different hypotheses of relationships. This study presents the results of a cladistic study encompassing 45 osteological and dental characters in the skull and mandible, as well as 13 soft‐tissue and behavioural characters. Analyzing extant pantherines with osteological data only resulted in two equally parsimonious trees, which differed only with respects to the jaguar, a taxon which shows morphological affinity to the tiger as well as the lion + leopard. Addition of soft‐tissue characters resolved this ambiguity, and led to markedly improved bootstrap values. The inclusion of fossil taxa did not have an impact on topology, but was important for a correct understanding of character evolution, due to the fossils having a combination of characters unlike those of any extant taxon. The clouded leopard is the most basal pantherine, followed by the snow leopard. The large pantherines are a well supported group, to which the snow leopard does not belong, contrary to some molecular studies. Panthera palaeosinensis is no tiger, but may be close to the stem group from which the tiger evolved. P. atrox and P. spelaea are not on the lion lineage, as traditionally assumed, but are successive outgroups to the lion + leopard, although the position of P. spelaea is tentative, but is supported by other lines of evidence such as brain anatomy. © The Willi Hennig Society 2008.     

Geography of dental polymorphism in the red fox Vulpes vulpes and its evolutionary implications

Frequency distributions of dental morphotype characters (groups of morphotypes from A to S) in 43 red fox Vulpes vulpes (Linnaeus, 1758) populations from the Holarctic region were analysed. Definite but different geographical gradients in morphotype dental patterns were found both in the Palearctic and Nearctic. In the Nearctic, a great number of characters present geographical gradient related to longitude whereas, in the Palearctic, gradient relates to latitude. Mean annual temperature and mean annual sum of precipitations play a significant role in shaping the geographical variation of morphotype characters. The shape of the teeth in the centre of the morphogenetic field is more heavily geo-climatically conditioned than the morphotype characters in the teeth at the ends of the cheek teeth field. There was an attempt to reconstruct the evolutionary changes in the morphotype dental pattern in the V. vulpes line. The morphotype pattern in the red fox dentition partially follows the phylogeographical evolutionary trends in Canidae in the northern hemisphere. However, the picture of morphotype variation is influenced by both earlier episodes of human interference (reintroductions of foxes in North America) and the recent phenomenon of heavy opportunism of the species.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 61–84.     

Reproductive performance of a lacertid lizard at the core and the periphery of the species' range

The range boundaries of organisms are frequently interpreted in terms of a decline in the extent to which the life histories of outer populations are able to adapt to local environmental conditions. To test this hypothesis, we compared the reproductive characteristics of two Iberian populations of the lizard Psammodromus algirus (Linnaeus, 1758). One of them (Lerma) is close to the northern edge of the species' range, whereas the other one (El Pardo) occupies a typical core habitat 200 km further south. Gravid females were captured in the field and transported to the lab for egg laying. Second clutches were less frequent at Lerma (where clutch size and clutch mass were larger for first than for second clutches) than at El Pardo. The total mass of both clutches combined was similar at both sites. Thus, the higher frequency of second clutches at El Pardo appeared to balance the between-sites difference in energy allocation to the first clutch. Females from Lerma laid more but smaller eggs than those from El Pardo. When incubated at the same temperature, eggs from Lerma hatched sooner even when controlling for between-sites differences in mean egg size. These differences are interpreted in the light of the advantages of early hatching and high fecundity in the northern population, as opposed to large offspring size in the core population. We conclude that the life-history traits studied show enough variation, presumably of an adaptive nature, to cope with environmental challenges at the edge of the species' range.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 87–96.