منابع مشابه
Deep-Time Phylogenetic Clustering of Extinctions in an Evolutionarily Dynamic Clade (Early Jurassic Ammonites)
Conservation biologists and palaeontologists are increasingly investigating the phylogenetic distribution of extinctions and its evolutionary consequences. However, the dearth of palaeontological studies on that subject and the lack of methodological consensus hamper our understanding of that major evolutionary phenomenon. Here we address this issue by (i) reviewing the approaches used to quant...
متن کاملMorphostructural constraints and phylogenetic overprint on sutural frilling in Late Jurassic ammonites
The functional signi cance of frilled septa and complex sutures in ammonoids has generated ongoing debate. The ‘classic’ hypothesis envisages ammonoid shells and septa as designed for resisting ambient hydrostatic pressure, complex sutures being the evidence of strength in shells for colonization of deep habitats. Here we address the ‘suture problem’, focusing on the analysis and interpretatio...
متن کاملMorphomechanics and Developmental Constraints in the Evolution of Ammonites Shell Form.
The idea that physical processes involved in biological development underlie morphogenetic rules and channel morphological evolution has been central to the rise of evolutionary developmental biology. Here, we explore this idea in the context of seashell morphogenesis. We show that a morphomechanical model predicts the effects of variations in shell shape on the ornamental pattern in ammonites,...
متن کاملSuture pattern formation in ammonites and the unknown rear mantle structure
Ammonite shells have complex patterns of suture lines that vary across species. The lines are formed at the intersection of the outer shell wall and the septa. The wavy septa can form if the rear mantle of the ammonite, which functions as the template, has a complex shape. Previous hypotheses assumed that the rear mantle is like a flexible membrane that can be folded by some physical force. The...
متن کاملcenomanian ammonites in the taghiabad section
in order to study the stratigraphic of sedimentary deposits of the cenomanian in kopeh dagh, the taghiabad section was selected. in the eastern kopeh dagh, the upper part of aitamir formation has this time range characteristic. the upper part of this formation includes shale and glauconitic sandstones and contains variety of ammonite fauna. ten genera and species of ammonites are found inside t...
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ژورنال
عنوان ژورنال: Geological Magazine
سال: 1924
ISSN: 0016-7568,1469-5081
DOI: 10.1017/s0016756800086180