Cladistic analysis of Albian heteromorph ammonites

A computer-based parsimony analysis of Albian heteromorph ammonites from the Tethyan and European faunal provinces is demonstrated. The results indicate that whilst Anisoceratidae, Baculitidae, Scaphitidae and Turrilitidae are monophyletic, Hamitidae is not. Previous studies of ammonite phylogenetics have used the coiling mode, ornamentation of the shell and the suture line as sources of characters. Comparison of the consistency and retention indices of these character suites indicates that whereas ornamentation is relatively consistent within clades, suture line morphology is highly homoplastic. The earliest known Sciponoceras , S. skipperae sp. nov., is described.     

Mode of life and habitat of scaphitid ammonites

Scaphitid ammonites (scaphites) are among the most common ammonites in the Upper Cretaceous of the U.S. Western Interior. We have examined species of Hoploscaphites from the Campanian and Maastrichtian Pierre Shale and Bearpaw Shale for clues about their mode of life and habitat. Like most other ammonites, scaphites exhibit determinate growth. The “morphogenetic countdown” begins at the point at which the shell departs from the spiral coil and develops into a shaft and recurved hook. This is accompanied by a reduction in the spacing of ribs and tubercles on the hook and the formation of a constriction and varix at the aperture. Internally, this coincides with a decrease in septal spacing. The common association of scaphites and benthic fossils (e.g., Inoceramus) is interpreted as reflecting oxygen-rich episodes in the history of the Western Interior Seaway. Habitat depths are estimated at less than 100 m, based on faunal associations and studies of the mechanical strength of the septa and siphuncle. Analyses of the isotopic composition of the shells suggest that the animals lived near the sea floor. The high angle of orientation of the aperture at maturity (approximately 100°) seems incompatible with a nektobenthic mode of life. The constricted aperture ending in a thin lip may also have restricted unimpeded movement of long, muscular arms protruding from the aperture. Adults were probably poor swimmers, based on a comparison of their musculature (as inferred from their muscle scars) with that of nautilus (assuming that such a comparison is valid). The lack of a hyponomic sinus on the midventer would have prevented the animal from extending its hyponome below the shell in order to swim forward. As a consequence, scaphites may have been limited in their movement to swimming backward or downward, and may have exploited a low-energy lifestyle, remaining at a single site for an extended period of time. They may have consumed small prey in the water column, which is consistent with the presence of an aptychus-type lower jaw.     

New occurrences of heteromorph ammonites in the Berriasian-Valanginian of the Crimean mountains

A new species, Bochianites (?) ambiguus sp. nov., is described from the Lower Berriasian of the Eastern Crimea. It is proposed that the name B. laevis Liu, 1988 be used instead of B. levis Arkadiev, 2008, as the former is a senior synonym and homonym. For the first time a species of the genus Leptoceras is described from the Upper Berriasian-Lower Valanginian of the former Soviet Union. Problems in the identification of heteromorph ammonites when they are partially preserved are discussed, and the geographical distribution and facial affinities of the heteromorph ammonite family Bochianitidae are considered.     

The evolution of the heteromorph and monomorph early cretaceous ammonites of the suborder Ancyloceratina Wiedmann

The relationship between the appearances of heteromorph and monomorph ammonoids and changes in the abiotic environment was studied. The correlation of these processes was examined for different intervals in the Early Cretaceous. The phylogeny of the superfamily Ancyloceratoidea Gill from the time of appearance of early heteromorphs (due to changes in ecological specialization) and the reversal process of the return to monomorph shells is examined for four superfamilies. The origin of monomorph ammonites of the superfamilies Theodoritoidea Baraboshkin et I. Michailova, superfam. nov., Douvilleiceratoidea Parona et Bonarelli, Parahoplitoidea Spath et Deshayesitoidea Stoyanow from heteromorph ancestral families Crioceratitidae Gill, Ancyloceratidae Gill, Hemihoplitidae Spath, and Heteroceratidae Spath in the superfamily Ancyloceratoidea Gill is suggested.     

Commensal anomiid bivalves on Late Cretaceous heteromorph ammonites from south‐west Japan

The heteromorph ammonite Pravitoceras sigmoidale from the Upper Cretaceous Seidan Formation (Izumi Group) in south‐west Japan is frequently encrusted by sessile anomiid bivalves. Fossils of P. sigmoidale with anomiids are often concentrated at the top of or just above turbidite sandstones. Projecting retroversal hooks and apertures of P. sigmoidale are usually intact, and some individuals are associated with jaw apparatuses near apertures. Anomiids are found on both sides and ventral peripheries of P. sigmoidale conchs, attached predominantly to body chambers. These modes of occurrence suggest that the encrustation by anomiids occurred not on post‐mortem floating or sunken carcasses but on live conchs and that these organisms were rapidly buried by turbidity current deposits shortly after death. Attachment to both flanks and ventral peripheries of the retroversal hooks may indicate that at least adult individuals of P. sigmoidale did not lie on the sea floor and did not drag their body chambers. It is suggested that fully mature individuals of this ammonite species lived for a long period of time after having formed the retroversal hook because a few generations of anomiids have colonized a single body chamber. Such colonization by anomiids is also observed on Didymoceras awajiense, which is considered to be the closely related ancestral species of P. sigmoidale. This anomiid–heteromorph ammonite commensal relationship might continue to persist in descendants during the course of evolution of these heteromorph ammonites.     

Recent parallel divergence in body shape and diet source of alewife life history forms

Recent work suggests that juvenile alewives (Alosa pseudoharengus) share similar phenotypes among independently derived landlocked (freshwater resident) populations. Based on this observation, it is possible that the alewife life history forms represent a case of parallel adaptive divergence. To further evaluate this hypothesis, we describe patterns of body shape divergence between anadromous and landlocked alewife life history forms using geometric morphometrics. Our results suggest that body shape differs significantly between juveniles of the alewife forms: anadromous fish were more robust, with larger heads and deeper caudal peduncles, while landlocked fish from three independently isolated populations were more fusiform with thinner caudal peduncles and smaller heads. These differences matched population level dietary patterns, which suggest that anadromous fish consumed more littoral resources than landlocked fish. Finding consistent differences across populations of the same form supports the notion that landlocked alewives have diverged from their anadromous ancestors in a parallel manner, in response to pressures associated with being isolated in freshwater lakes. Comparing alewife phenotypes to expectations from the literature suggests that neither migration distance of the population, nor the relative availability of habitats in each lake, are likely drivers of the pattern we report. Instead, the pattern is consistent with the hypothesis that divergence between alewife forms results from the distinct effects of each form on its zooplankton prey.     

Mode of miniaturisation influences body shape evolution in New World anchovies (Engraulidae)

We explored the macroevolutionary dynamics of miniaturisation in New World anchovies by integrating a time-calibrated phylogeny, geometric morphometrics and phylogenetic comparative methods. We found that the paedomorphic species Amazonsprattus scintilla occupies a novel region of shape space, while the dwarf species Anchoviella manamensis has an overall shape consistent with other anchovies. We found that miniaturisation did not increase overall clade disparity in size or shape beyond the expectations of Brownian motion, nor were there differences in rates of size or shape evolution among clades. Overall, our study shows that while the mode of miniaturisation influences shape evolution, the phenotypic novelty produced by the evolution of miniaturisation did not seem to alter macroevolutionary dynamics.     

Soft–part preservation in heteromorph ammonites from the Cenomanian–Turonian Boundary Event (OAE 2) in north–west Germany

Abstract: From thinly laminated marlstones of the Hesseltal Formation, representing the Late Cenomanian Oceanic Anoxic Event (OAE) 2, at Lengerich in the Teutoburger Wald (Westfalen, north‐west Germany), 17 sediment‐compacted baculitid ammonites with carbonised and partially phosphatised soft parts are recorded. Some preserve remains of the buccal mass, including jaws (occasionally articulated) and radulae, as well as of the cephalic cartilage, such as eye capsules. Such have not yet been recorded previously for the order Ammonoidea. In addition, originally unmineralised parts found preserved in these specimens include extensive portions of the digestive tract, the siphonal tube, false colour patterns (megastriae), as well as traces of what would appear to be the oviduct. At the same levels, patches with numerous isolated horny upper and rarer lower jaws as well as radulae occur; these may represent regurgitates or faeces of larger predators. The cephalopod remains described were deposited in an epicontinental setting, possibly at palaeodepths between 200 and 600 m. In this particular Late Cretaceous fossil Lagerstätte, upper jaws and anaptychi of ammonites rank among the commonest fossils.     

Swimming abilities of ammonites and limitations

Using some typial ammonites from the Posidonia shales, the aperture orientation, the ideal direction of propulsive thrust, the stability and the buoyancy of the living animals and of the empty shells were investigated as a function of the body chamber length. The emerging limitations indicate that ammonites were hardly suited for a nectonic mode of life. Only in case of favourable conditions empty shells could ascend to the surface and drift.     

The true body shape of rorqual whales

Live Sei and Minke whales were observed underwater off Japan by a new method using commercial catcher boats. A non-explosive harpoon was fired into the tail region of a whale and a diver approached the "tethered" live whale.
After initial flurries, Sei and Minke whales swam steadily ahead of the catcher and could easily be approached by a diver. They took absolutely no notice of the diver. Live Sei and Minke whales kept their mouths tight shut all the time, but immediately after death the lower jaw always fell open. Little blood was emitted from the harpoon wound. The flippers were raised laterally when a whale surfaced and held against the sides of the body when it dived.
The body shape of both rorqual species was streamlined and the throat region was quite flat, not in any way dilated. The classical baggy-throated illustrations of rorqual whales do not show the true shape of live animals.
Sperm whales harpooned by the same method swam about wildly, shed much blood and could not be observed underwater.     

Transgenesis changes body and head shape in Pacific salmon

Insertion of a pOnMTGH1 gene construct into coho salmon altered centroid size significantly (P<0·05). The dorsal caudal peduncle and abdominal regions were also distinctly enhanced in transgenic fish when compared to controls. Shape change patterns of both whole body and syncranium were prominent.     

Genetics of body shape and armour variation in threespine sticklebacks

Patterns of genetic variation and covariation can influence the rate and direction of phenotypic evolution. We explored the possibility that the parallel morphological evolution seen in threespine stickleback (Gasterosteus aculeatus) populations colonizing freshwater environments is facilitated by patterns of genetic variation and covariation in the ancestral (marine) population. We estimated the genetic (G) and phenotypic (P) covariance matrices and directions of maximum additive genetic (g(max) ) and phenotypic (p(max) ) covariances of body shape and armour traits. Our results suggest a role for the ancestral G in explaining parallel morphological evolution in freshwater populations. We also found evidence of genetic constraints owing to the lack of variance in the ancestral G. Furthermore, strong genetic covariances and correlations among traits revealed that selective factors responsible for threespine stickleback body shape and armour divergence may be difficult to disentangle. The directions of g(max) and p(max) were correlated, but the correlations were not high enough to imply that phenotypic patterns of trait variation and covariation within populations are very informative of underlying genetic patterns.     

A new body shape index predicts mortality hazard independently of body mass index

Background

Obesity, typically quantified in terms of Body Mass Index (BMI) exceeding threshold values, is considered a leading cause of premature death worldwide. For given body size (BMI), it is recognized that risk is also affected by body shape, particularly as a marker of abdominal fat deposits. Waist circumference (WC) is used as a risk indicator supplementary to BMI, but the high correlation of WC with BMI makes it hard to isolate the added value of WC.

Methods and Findings

We considered a USA population sample of 14,105 non-pregnant adults () from the National Health and Nutrition Examination Survey (NHANES) 1999–2004 with follow-up for mortality averaging 5 yr (828 deaths). We developed A Body Shape Index (ABSI) based on WC adjusted for height and weight: ABSI had little correlation with height, weight, or BMI. Death rates increased approximately exponentially with above average baseline ABSI (overall regression coefficient of per standard deviation of ABSI [95% confidence interval: –]), whereas elevated death rates were found for both high and low values of BMI and WC. (–) of the population mortality hazard was attributable to high ABSI, compared to (–) for BMI and (–) for WC. The association of death rate with ABSI held even when adjusted for other known risk factors including smoking, diabetes, blood pressure, and serum cholesterol. ABSI correlation with mortality hazard held across the range of age, sex, and BMI, and for both white and black ethnicities (but not for Mexican ethnicity), and was not weakened by excluding deaths from the first 3 yr of follow-up.

Conclusions

Body shape, as measured by ABSI, appears to be a substantial risk factor for premature mortality in the general population derivable from basic clinical measurements. ABSI expresses the excess risk from high WC in a convenient form that is complementary to BMI and to other known risk factors.     

A new method for determining cross-sectional shape and area of soft tissues

Assessment of the mechanical properties of soft tissues requires accurate measurement of the cross-sectional area. To date, techniques for determining cross-sectional areas of ligaments and tendons have been less than ideal due to the tissues' complex geometries and the fact that they deform easily under an applied external load. A new procedure has been developed for determining the cross-sectional area by means of an image reconstruction technique based on measurements from collimated laser beams. Using this procedure, the actual shape of the specimen cross-section can also be determined. The results are demonstrated to be highly accurate, and this methodology does not require mechanical contact with the specimen.