Primitive Features (primitive + feature)

Distribution by Scientific Domains

Selected Abstracts

Heddleichthys, a new tristichopterid genus from the Dura Den Formation, Midland Valley, Scotland (Famennian, Late Devonian)

Daniel Snitting
Abstract A new tristichopterid genus, Heddleichthys, from the Famennian of Scotland is described based on material previously assigned to a number of different genera, including Glyptopomus, Gyroptychius and Eusthenopteron. The validity of the new genus is established by a discussion of the reasons for the invalidity of the previous assignments. Heddleichthys is characterized by a combination of derived and primitive tristichopterid features. Derived features include the presence of symphyseal dentary fangs and premaxillary pseudofangs, a diamond-shaped symmetric caudal fin, a low posterodorsal expansion of the maxilla, and a posteriorly positioned kite-shaped pineal series. Primitive features include a postorbital and jugal contribution to the orbital margin and a parasphenoid with a ventral keel. External dermal bones are rather poorly preserved in the referred material, with few easily discernible sutures. The holotype specimen, a three-dimensionally preserved skull, was scanned by computed tomography to reveal well-preserved internal dermal bones, including entopterygoids, vomers and parasphenoid. There is no preserved endoskeletal material. As the first representative of derived tristichopterids described from Britain, Heddleichthys lends support to the idea that faunal dispersion between Gondwana and Laurussia in the Late Devonian was widespread. Derived tristichopterids have been described from all continents except South America. In contrast, the basal tristichopterids Eusthenopteron and Tristichopterus are still only described from Laurussia. [source]

Moral Incapacity and Huckleberry Finn

RATIO, Issue 1 2001
Craig Taylor
Bernard Williams distinguishes moral incapacities , incapacities that are themselves an expression of the moral life , from mere psychological ones in terms of deliberation. Against Williams I claim there are examples of such moral incapacity where no possible deliberation is involved , that an agent's incapacity may be a primitive feature or fact about their life. However Michael Clark argues that my claim here leaves the distinction between moral and psychological incapacity unexplained, and that an adequate understanding of the kind of examples I suggest must involve at least some implicit reference to deliberation. In this paper I attempt to meet Clark's objection and further clarify my account of primitive moral incapacities by considering an example from Mark Twain's Huckleberry Finn. What this example shows, I argue, is how our characterization of an agent's response as a moral incapacity turns not on the idea of deliberation but on the way certain primitive incapacities for action are connected to a larger pattern of response in an agent's life, a pattern of response that itself helps to constitute our conception of that agent's character and the moral life more generally. [source]

The phylogeny of the red panda (Ailurus fulgens): evidence from the forelimb

Rebecca E. Fisher
Abstract Within the order Carnivora, the phylogeny of the red panda (Ailurus fulgens) is contentious, with morphological and molecular studies supporting a wide range of possible relationships, including close ties to procyonids, ursids, mustelids and mephitids. This study provides additional morphological data, including muscle maps, for the forelimb of Ailurus, based on the dissection of four cadavers from the National Zoological Park, Washington, DC, USA. The red panda forelimb is characterized by a number of primitive features, including the lack of m. rhomboideus profundus, a humeral insertion for m. cleidobrachialis, the presence of mm. brachioradialis, articularis humeri and coracobrachialis, a single muscle belly for m. extensor digitorum lateralis with tendons to digits III,V, four mm. lumbricales, and the presence of mm. flexor digitorum brevis manus, adductores digiti I, II and V, and abductor digiti I and V. Red pandas resemble Ailuropoda, mustelids and some procyonids in possessing a soft tissue origin of m. flexor digitorum superficialis. In addition, red pandas are similar to ursids and procyonids in having a variable presence of m. biceps brachii caput breve. Furthermore, Ailurus and some ursids lack m. rhomboideus capitis. The forelimb muscle maps from this study represent a valuable resource for analyzing the functional anatomy of fossil ailurids and some notes on the Miocene ailurid, Simocyon batalleri, are presented. [source]

Isolation of the plastid FtsZ gene from Cyanophora paradoxa (Glaucocystophyceae, Glaucocystophyta)

Mayuko Sato
SUMMARY Plastids of glaucocystophytes are termed cyanelles and retain primitive features, such as a peptidoglycan wall. We isolated a full-length prokaryotic plastid division gene, FtsZ, from the glaucocystophyte alga Cyanophora paradoxa Korshikov (CpFtsZ-cy). CpftsZ-cy has a chloroplast-targeting signal at the N-teminus. Immunofluorescence microscopy showed that CpFtsZ-cy forms a ring-like structure at the division plane of cyanelles. [source]

Dicotyledonous wood anatomy and the APG system of angiosperm classification

The recently proposed classification by the Angiosperm Phylogeny Group (APG) of angiosperms based on monophyletic groups as recognized mainly by molccular analysis is used here to discuss wood anatomical diversity patterns at the ordinal level. The APG orders are compared with the most recent ,classical' orders as listed in the second edition of 7 h e Plant Book for ,improved' or ,deteriorated' wood anatomical coherence. Although homoplasy in wood anatomical characters, largely due to ecoloqical adaptations, limits the value of wood anatomy at higher levels of classification, many families and orders tend to have characteristic combinations of microscopic wood features. Out of the 29 APG dicot orders, seven (Aquifoliales, Cucurbitales, Gentianales, Geraniales, Myrtales, Sapindales, Saxifragales) show an increase in wood anatomical homogeneity relative to their ,classical' predecessors; four APG dicot orders (Apiales, Ericales, Fabales, and Rosales) show a drcrrase, although within the orders several suprafamilial subclades are homogeneous. For the remaining 18 orders. wood anatomical diversity remains about the same as in previous classfications or the APG ordinal composition is almost identical to the ,classical' composition. The results support the value of both molecular markers and wood anatomical characters in phylogenetic classification. Because the ,classical' ordinal classifications have been partly inspired by wood anatomical information, one might have expected a ?greater wood anatomical coherence in them than in the largely molecularly delimited APG orders if wood anatomy did not provide significant phylogenetic sisgnals at higher taxonomic levels. The reverse appears to be the case. Among the wood anatomical characters included in the comparison, vestured intervessel pits, large and simple ray parenchyma pits, and sometimes also wide and tall rays appear to characterize orders. Some orders tend to be characterized by a combination of ,primitive' features in the Baileyan sense: scalariform perforations, fibres with distinctly bordered pits, apotracheal parenchyma, and heterocellular rays. This raises the question as to whethcr in thcsc cladcs this entire combination of characteristics should not he viewrd as synapomorphic rather than symplesiomorphic. [source]