Conodont affinity and chordate phylogeny DONOGHUE, PHILIP C. J.; FOREY, PETER L.; ALDRIDGE, RICHARD J.
Biological reviews of the Cambridge Philosophical Society,
05/2000, Letnik:
75, Številka:
2
Journal Article
Recenzirano
Current information on the conodonts Clydagnathus windsorensis (Globensky) and Promissum pulchrum
Kovács–Endrödy, together with the latest interpretations of conodont hard tissues, are reviewed and ...it is concluded
that sufficient evidence exists to justify interpretation of the conodonts on a chordate model. A new
phylogenetic analysis is undertaken, consisting of 17 chordate taxa and 103 morphological, physiological and
biochemical characters; conodonts are included as a primary taxon. Various experiments with character
coding, taxon deletion and the use of constraint trees are carried out. We conclude that conodonts are
cladistically more derived than either hagfishes or lampreys because they possess a mineralised dermal
skeleton and that they are the most plesiomorphic member of the total group Gnathostomata. We discuss
the evolution of the nervous and sensory systems and the skeleton in the context of our optimal phylogenetic
tree. There appears to be no simple evolution of free to canal-enclosed neuromasts; organised neuromasts
within canals appear to have arisen at least three times from free neuromasts or neuromasts arranged within
grooves. The mineralised vertebrate skeleton first appeared as odontodes of dentine or dentine plus enamel
in the paraconodont/euconodont feeding apparatus. Bone appeared later, co-ordinate with the development
of a dermal skeleton, and it appears to have been primitively acellular. Atubular dentine is more primitive
than tubular dentine. However, the subsequent distribution of the different types of dentine (e.g.
mesodentine, orthodentine), suggests that these tissue types are homoplastic. The topology of relationships
and known stratigraphic ranges of taxa in our phylogeny predict the existence of myxinoids and
petromyzontids in the Cambrian.
To analyse the introduction of the Couder manoeuvre in our level 3 maternity unit shortly after its introduction in 2019. Then, to evaluate and compare the rate of perineal injuries between 2017, ...when the manoeuvre was not performed at all, and 2020.
A single-centre retrospective study of patients who delivered a singleton eutociously at term from 1 January to 31 December 2017 and 2020.
In total, 2930 records were analysed. The Couder manoeuvre rate was 32.12% in 2020. A change in the distribution of perineal lesions was observed: the rate of intact perineum increased (P<0.001), while 2nd degree lesions decreased between 2017 and 2020 (P<0.05). The 1st degree perineum and obstetric anal sphincter injuries remained stable. The rate of episiotomy decreased significantly by almost a factor of 7.
The practice of the Couder manoeuvre can be implemented fairly quickly after training of the actors with nearly a third of normal deliveries at term concerned one year after its introduction. This manoeuvre seems, in our practice, to have contributed to the reduction, as previously reported, of the rate of second degree perineal injuries.
Taxonomy and fossils: a critical appraisal Forey, Peter L.; Fortey, Richard A.; Kenrick, Paul ...
Philosophical transactions of the Royal Society of London. Series B. Biological sciences,
04/2004, Letnik:
359, Številka:
1444
Journal Article
Recenzirano
Odprti dostop
Many compendia at the species, genus and family levels document the fossil record, but these are not standardized, nor usually critical in content, and few are available on the World Wide Web. The ...sampling of the available record is good for organisms with fossilizable parts, but preservational constraints on the entire morphology, life history and geographical distribution lead to difficulties in recognizing and naming species. We recommend abandoning some of the palaeontological species concepts such as chronospecies and stratospecies, and we advocate species recognition based on unique combinations of characters. The compilation of species lists is extremely time consuming, and given the inherent problems we suggest that compilation of generic lists is a more achievable goal because genera are recognized by definitive morphological characters. In calculating taxon duration, care must be taken to distinguish between mono-, para- and polyphyletic groups, the first being the only reliable unit for use in calculating diversity curves. We support the inclusion of fossils into classifications based on Recent organisms, but we recognize some of the problems this may pose for standard Linnaean classifications. Web-based taxonomy is the way forward, having the advantages of speed and currency of information dissemination, universal access with links to primary literature and increasingly sophisticated imagery. These advantages over conventional outlets will only be realized with careful Web design and a commitment to maintenance.
The Cretaceous-Tertiary biotic transition Macleod, N; Rawson, P. F; Forey, P. L ...
Journal of the Geological Society,
03/1997, Letnik:
154, Številka:
2
Journal Article
Recenzirano
Mass extinctions are recognized through the study of fossil groups across event horizons, and from analyses of long-term trends in taxonomic richness and diversity. Both approaches have inherent ...flaws, and data that once seemed reliable can be readily superseded by the discovery of new fossils and/or the application of new analytical techniques. Herein the current state of the Cretaceous-Tertiary (K-T) biostratigraphical record is reviewed for most major fossil clades, including: calcareous nannoplankton, dinoflagellates, diatoms, radiolaria, foraminifera, ostracodes, scleractinian corals, bryozoans, brachio-pods, molluscs, echinoderms, fish, amphibians, reptiles and terrestrial plants (macrofossils and palynomorphs). These reviews take account of possible biasing factors in the fossil record in order to extract the most comprehensive picture of the K-T biotic crisis available. Results suggest that many faunal and floral groups (ostracodes, bryozoa, ammonite cephalopods, bivalves, archosaurs) were in decline throughout the latest Maastrichtian while others (diatoms, radiolaria, benthic foraminifera, brachiopods, gastropods, fish, amphibians, lepidosaurs, terrestrial plants) passed through the K-T event horizon with only minor taxonomic richness and/or diversity changes. A few microfossil groups (calcareous nannoplankton, dinoflagellates, planktonic foraminifera) did experience a turnover of varying magnitudes in the latest Maastrichtian-earliest Danian. However, many of these turnovers, along with changes in ecological dominance patterns among benthic foraminifera, began in the latest Maastrichtian. Improved taxonomic estimates of the overall pattern and magnitude of the K-T extinction event must await the development of more reliable systematic and phylogenetic data for all Upper Cretaceous clades.
In order to better understand the parameters that drove evolution of actinopterygian fishes from the Late Jurassic to the Late Cretaceous (this being the time of diversification of crown group ...teleosts, by far the dominant fish group today), we define three environmental indicators, which are detectable as concordant patterns in the geological and fossil records. These are 1) freshwater radiations, 2) vicariant events and 3) sea temperature. We mapped the indicators onto a phylogeny of the Late Jurassic–Palaeocene actinopterygian taxa, and plotted the variations against time for each of the indicators. Our results show that for several of the marine clades, diversity is positively correlated with sea temperature and for one clade negatively correlated with sea temperature. The marine radiation is very important in the mid-Cretaceous, especially in the Tethys, which may have been a centre of origin for some clades. Vicariant events occurred in both marine and freshwater groups, and are abundant during the opening of the south Atlantic in the Early Cretaceous. Freshwater radiations, forming in some cases species flocks, are especially evident in the basal Cretaceous in Asia. Although these results are affected by biases related to the fossil record and to its study, we propose that these global patterns are genuine and reflect the strong impact of the Earth system on the evolution of fishes in the Late Mesozoic.
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