Ammonites are prominent in macroevolutionary studies because of their abundance and diversity the fossil record, but paleobiology position marine food web not well understood due to lack preserved soft tissue. We present three-dimensional reconstructions buccal apparatus Mesozoic ammonite Baculites with use synchrotron x-ray microtomography. Buccal mass morphology, combined coexistence remains found mass, suggests that these ammonites fed on plankton. This diet may have extended all...

Although the calcitic hard parts of belemnites (extinct Coleoidea) are very abundant fossils, their soft hardly known and mode life is debated. New fossils Jurassic belemnitid Acanthoteuthis provided supplementary anatomical data on fins, nuchal cartilage, collar complex, statoliths, hyponome radula. These yielded evidence pelagic habitat, nektonic habit high swimming velocities. The new morphological characters were included in a cladistic analysis, which confirms position Belemnitida stem...

ABSTRACT Heteromorphs are ammonoids forming a conch with detached whorls (open coiling) or non‐planispiral coiling. Such aberrant forms appeared convergently four times within this extinct group of cephalopods. Since Wiedmann's seminal paper in journal, the palaeobiology heteromorphs has advanced substantially. Combining direct evidence from their fossil record, indirect insights phylogenetic bracketing, and physical as well virtual models, we reach an improved understanding heteromorph...

Externally shelled cephalopods were important elements in open marine habitats throughout Earth history. Paleotemperatures calculated on the basis of oxygen isotope composition their shells can provide insights into ancient systems as well ecology this group organisms. In some sedimentary deposits, however, aragonitic shell ammonite or nautilid is poorly not preserved at all, while calcitic structures belonging to jaws are present. This study tests for first time if jaw fossil be used a...

The microstructure of aptychi (bivalved calcareous coverings on lower jaws) three genera Late Cretaceous Ancyloceratina, Baculites, Polyptychoceras and Jeletzkytes is described for the first time basis well-preserved in situ material from Western Interior USA Hokkaido, Japan. Optical scanning electron microscope observations polished median cross-sections reveal some variation their relative size, shape among genera. aptychus Baculites composed two calcitic layers: one with tilted lamellae...

Abstract Beaks are among the few hard parts of coleoid cephalopods and informative for species identification. Although mandible shape has been shown to be adaptive in many vertebrate taxa, it suggested that beaks does not bear any ecological signal. Yet, previous studies only explored beak 2D none have provided an in‐depth investigation potential relationship with variables such as habitat use or diet. The goal present study was understand whether variation cephalopod reflects ecology...

Although soft tissues of coleoid cephalopods record key evolutionary adaptations, they are rarely preserved in the fossil record. This prevents meaningful comparative analyses between extant and forms, as well development a relative timescale for morphological innovations. However, unique 3-D tissue preservation Vampyronassa rhodanica (Vampyromorpha) from Jurassic Lagerstätte La Voulte-sur-Rhône (Ardèche, France) provides unparalleled opportunities observation these oldest likely...

Abstract Palaeontological data are key elements for inferring ancestral character states and the assembly of complexes, but cephalopod fossils preserving soft tissues very rare. The exceptionally well‐preserved, unique specimen Jurassic Proteroctopus ribeti Fischer & Riou from Lagerstätte La‐Voulte‐sur‐Rhône ( c . 165 Ma, France) is one few fossil octopod related taxa, rarely considered in evolutionary studies. In this paper, we used synchrotron microtomography to reappraise its external...

We describe here a new Lawrenciella Poplin, 1984 specimen from the Upper Carboniferous (Missourian, Pennsylvanian) Oklahoma, USA. This is three dimensionnally preserved in phosphatic nodule. It was scanned by X-Ray microtomography. The neurocranium shows some morphological differences schaefferi 1984, which might represent individual variability. parasphenoid and pair of intercalar bones are associated with braincase. presence intercalars as an anterior extension covering otico-occipital...

Tanabe, K., Landman, N.H. & Kruta, I. 2011: Microstructure and mineralogy of the outer calcareous layer in lower jaws Cretaceous Tetragonitoidea Desmoceratoidea (Ammonoidea). Lethaia, Vol. 45, pp. 191–199. Based on differences their relative size, overall shape, structure degree development an calcified covering, Ammonoidea have been classified into four morphotypes: normal, anaptychus, aptychus rhynchaptychus types. However, detailed microstructural mineralogical comparison these...

Abstract Eight coleoid genera have so far been described from the Callovian‐aged La Voulte‐sur‐Rhône Lagerstätte ( c . 165 Ma; Ardèche, France), a locality noted for its unique three‐dimensional preservation of soft tissues. Here, we used high resolution x‐ray‐based imaging methods, in conjunction with reflectance transformation imaging, to study tissues previously undescribed locality. This analysis identified both an ink sac and internal light organs, combination defence mechanisms present...

We report on well-preserved upper and lower jaws found inside the body chambers of two specimens Didymoceras nebrascense (Meek Hayden, 1856) from Upper Cretaceous Pierre Shale USA. The finds are described compared to existing material, their possible functions discussed.

Abstract: Radular teeth occur between the jaws in two specimens of Late Cretaceous scaphitid ammonite Rhaeboceras halli (Meek and Hayden, 1856) from Western Interior United States. The detailed morphology has been revealed by propagation phase contrast X‐ray synchrotron microtomography. Each row radula R. consists a total seven (a central rachidian, pairs lateral one pair marginal teeth), as other known ammonoid radulae, although tooth could not be confirmed examined. are multicuspid robust,...

Exceptionally well-preserved radulae and lower jaws found both inside the body chamber of Cravenoceras fayettevillae (Mississippian) in isolated nodules (Mississippian Pennsylvanian) were analysed using CT scan synchrotron propagation phase-contrast tomography. This approach reveals new anatomical details allowing us to investigate wear, preservation muscle insertion buccal mass Goniatitina. For comparison, Recent cephalopod also investigated. The radula Goniatitina consists nine elements...

We describe a small crab inside the phragmocone of heteromorph cephalopod Baculites sp. smooth from Gammon Ferruginous Member (lower Campanian) Pierre Shale in Butte County, South Dakota. The Ferricorda kimberlyae (Bishop, 1987) is well preserved with its carapace and pereiopods parallel to between two septa phragmocone. Because superb preservation, specimen unlikely have been washed into probably retreated chamber avoid predation or molt was subsequently buried by an influx rapid...

Abstract In the last few decades, hook‐like structures have been reported in Mesozoic ammonite family Scaphitidae. Despite their exceptional preservation and debates about function, no detailed reconstruction has available until now. For first time, we describe composition details of morphology these found body chambers six specimens Campanian Rhaeboceras halli (Meek & Hayden) using high resolution x‐ray imaging. The are composed a thin layer brushite. base each hook is open on one side...

Although patchy, the fossil record of coleoids bears a wealth information on their soft part anatomy. Here, we describe remains axial nerve cord from both decabrachian (Acanthoteuthis, Belemnotheutis, Chondroteuthis) and octobrachian (Plesioteuthis, Proteroctopus, Vampyronassa) Jurassic. We discuss some hypotheses reflecting possible evolutionary drivers behind neuroanatomical differentiation coleoid arm crown. also propose potential links between habitat depth, mode life evolution...

Abstract Ammonite soft body remains are rarely preserved. One of the biggest enigmas is morphology ammonite brachial crown that has, up till now, never been recovered. Recently, mysterious hook-like structures have reported in multiple specimens Scaphitidae, a large family heteromorph Late Cretaceous ammonites. A previous examination these revealed they belong to Their nature, however, remained elusive. Here, we exploit tomographic data study their arrangement space order clarify this...