摘要:

Rockycampacanthus milesin.gen., n.sp.is described from a single jaw from the Rocky Camp member of Lower Devonian Buchan Group, E Victoria.Rockycampacanthusdiffers from other ischnacanthiforms in having large multicuspidate teeth with dual rows of secondary cusps forming a posteromesial flange, a mesial tooth row beginning opposite the fourth cusp of the main tooth row, and in the gnathal bone being deepest in the anterior half.Taemasacanthus errolin. gen., n. sp.is described from several jaw bones from the Lower Devonian Murrumbidgee Group, New South Wales.Taemasacanthushas a well developed posterolabial flange with secondary cusps developed, vertical rows of denticles on the cusps of the main tooth row and a well developed mesial tooth row separated from the main row by a prominent ridge. The labial face of the jaw has a circular ridge which may have supported labial cartilages. The complex mandibular joint in climatiforms, acanthodiiforms and some primitive sharks differs from the simple jaw articulation of ischnacanthids. It is suggested that ischnacanthids are the plesiomorphic sister group to climatiforms plus acanthodiiforms. The interrelationships of ischnacanthids, climatiforms and acanthodiforms are discussed.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1986.tb01339.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

A new phylogeny of the Superfamily Rhinocerotoidea is proposed, based upon an analysis of shared derived characters of the skull, teeth and skeleton.Hyrachyusis considered the primitive sister‐taxon of the three rhinocerotoid families (Amynodontidae, Hyracodontidae, Rhinocerotidae), and the amynodonts appear to be the sister‐group of hyracodonts and rhinocerotids. The relationships of primitive hyracodonts and rhinocerotids are clarified.MenocerasandPleuroceras(new Subfamily Menoceratinae) are removed from the Diceratheriinae, since they appear to be more closely related to higher rhinoceroses than they are toDiceratherium.Of the three major monophyletic groups of higher rhinocerotids (aceratherines, teleoceratines and rhinocerotines), the last two groups are more closely related to each other than either is to aceratherines.ToxotheriumandSchizotheroidesare tentatively removed from the Rhinocerotoidea and placed in the Lophiodonti

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1986.tb01340.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The radiation of the endemic Jamaican land snail genusSagdais examined through analysis of the comparative shell morphology, anatomy, ecology and biogeography of the four species inhabiting north‐central Jamaica:S. centralissp. nov.,S. spei, S. bondiandS. montegoensis.The species are all rather similar in their morphology and ecology. The shells show some differences in the presence or absence of internal lamellae, the position of the lamellae, the form of the depression in the centre of the base, the regularity of sculpture (low ribs) and the pattern of microsculpture. Slight differences in the form of the radular teeth are found between some species. The structure of the secondary ureter is peculiar: in all species it is open shortly behind the mantle collar, then branches into two closed tubes which open separately on the outside of the mantle collar. Despite its great complexity, the reproductive system is rather uniform among species; differences are seen in the number of pockets that form spines on the spermatophore. The complex, three‐branched spermatophore is formed within the entire epiphallar branch of the penis, whereas the appendicular branch apparently assumes the copulatory function.When inactive, all species are found associated with rocks or, less commonly, among leaf litter. Activity occurs primarily at night and mostly on leaf litter rather than rocks. The snails eat dead plant material, including a variety of plant species. All species (with the possible exception ofS. montegoensis) are ovoviviparous. They overlap broadly in the range of climates occupied. The geographic ranges of the four species are overlapping, althoughSagda bondihas a parapatric distribution in relation to the western speciesS. grandis.Fossil and subfossil evidence shows that shifts in the ranges of the species have occurred in the late Quaternary; Pleistocene‐Holocene environmental changes, habitat destruction by man, and possibly other environmental changes during historical times are probably involved. Radiations of other land snail groups on tropical islands have generally produced greater morphological and ecological differentiation than inSagda.Allopatric or parapatric species distributions appear to be more common in other land snail radia

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1986.tb01341.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY