(1961) - The Liassic ammonite zones and subzones of the north-west European Province. (1918) - Yorkshire Type Ammonites II (Part XVI), London, 112-116, 8 Pls.ĭean W.T., Donovan D.T. Monograph of the Palaeontographical Society, London, 3: 57-144.īuckman S.S. (1889) - A Monograph on the Inferior Oolite Ammonites of the British Islands. Enciclopeédie Méthodique, 6: 1-344.īuckman S.S. Philosophical Transactions of the Royal Society A, 373: 20140254.īruguière J.G. (2015) - Deep questions about the nature of early-life signals: a commentary on Lister (1673) ‘A description of certain stones figured like plants’. Journal de Conchyliologie, Paris, 48: 122-164.īrasier M. (1900) - Les Ammonites du Calcaire Rouge Ammonitique (Toarcien) de l’Ombrie. This alternative view clarifies the taxonomic approach held by many authors, proving the coherency of their taxonomic work rather than their attitude at a superficial evaluation of diagnostic traits.īellini R. In contrast with this view, it is herein argued that, on one hand, the specimen illustrated by Buckman, in quality of holotype or neotype, differs from Lister’s drawing to a point that it may not be the same specimen on the other hand, Lister’s drawing (never formally invalidated as holotype) could have been legitimately considered representative also of those faintly grooved Hildoceras now assigned to Hildoceras lusitanicum Meister, 1913. Nevertheless, several authors insisted on referring faintly grooved specimens to Hildoceras bifrons, an attitude thus envisaged as due to their negligence or inaccuracy. Buckman’s illustration assessed the well-carved spiral groove as a distinctive feature of the holotype and a trademark of the species. Buckman (1918) provided a photographic illustration of a specimen he interpreted as corresponding to the holotype, until then represented by a drawing described by Lister (1678) as Ammonis cornu. Since the XIX century, however, a number of morphotypes assigned to Hildoceras bifrons (many of which from the Apennines and other Italian localities) lacked a neat spiral groove, replaced by a shallow, variably evident and discontinuous inflection. Inter-demic and phylogenetic variability are noticeable, also affecting the most distinctive morphological trait: the spiral groove along the whorl flank. Hildoceras bifrons (Bruguière, 1789) is a cosmopolite ammonite species from the Lower Jurassic of the Boreal and Mediterranean (Tethys) palaeogeographical provinces. History of Palaeontology ammonites scientific illustrations Toarcian Rosso Ammonitico.
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