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| Keywords: The Quarterly journal of the Geological Society of London (13205249514).jpg 46 PROCEEDINGS OF THE GEOLOGICAL SOCIETY <br> with the scapula This interpretation seems to be supported by an <br> analogous bar in the amphibian shoulder-girdle This considered <br> Fig 2 ” Shoulder-girdle of Plesiosaurus type ventral view <br> osty the omosternum ; pc the prsecoracoid ; sc the scapula ; co the coracoid ; <br> H the humerus <br> praecoracoid by W K Parker regarded as clavicle by Wiedersheimer <br> thought to comprise both praecoracoid and clavicle by Hoffmann is <br> primitively a simple cartilaginous rod extending ventrally from the <br> scapula towards the middle line of the body Later an ectosteal splint <br> forms on its front border and growing more or less sheathes it the rod <br> itself meanwhile undergoing a variable amount of endosteal ossifi- <br> cation ; and when these two processes of ossification are completed a <br> slight longitudinal furrow may be the only trace of the dual origin <br> of the bar It is evident that the ectosteal splint alone can have any <br> pretention to homology with the clavicles of higher vertebrates ; and <br> I imagine that its intimate association with the cartilaginous rod <br> which is segmented off by longitudinal fissure from the coracoid and <br> is therefore unmistakably praecoracoid was one of the considerations <br> that led Prof Parker to regard the bar in its entirety as praecora- <br> coid and to deny the occurrence of true clavicles in Batrachia a view <br> which has much in favour of it In Chelonia fig 3 however the <br> ambiguity so puzzling in Batrachia disappears They also have a <br> similarly placed ventral bar which except in very immature indi- <br> viduals is as in Plesiosaurus confluent with the glenoid part of the <br> scapula from which it extends inwards towards the middle line of <br> the body Early comparative anatomists regarded this as an acro- <br> mion or clavicle the view I think still held by Prof R Owen Of <br> its homology with the analogous bar in Plesiosaurus and Nothosaurus <br> I myself have no doubt ; and if it be clavicle in the Chelonian it is so <br> in Plesiosaurus and Nothosaurus and thus clavicles would be present <br> in Sauropterygia as in Ichthyopterygia But in Chelonia as Prof W 36929351 113681 51125 Page 46 Text 39 http //www biodiversitylibrary org/page/36929351 1883 Geological Society of London NameFound Batrachia NameConfirmed Batrachia EOLID 12111331 NameBankID 5952690 NameFound Chelonia NameConfirmed Chelonia EOLID 19671 NameBankID 4935336 NameFound Nothosaurus NameConfirmed Nothosaurus EOLID 4532508 NameBankID 4260130 NameFound Plesiosaurus NameConfirmed Plesiosaurus EOLID 4532515 NameBankID 4302234 NameFound Sauropterygia NameConfirmed Sauropterygia EOLID 4532436 Biodiversity Heritage Library The Quarterly journal of the Geological Society of London v 39 1883 Geology Periodicals Smithsonian Libraries bhl page 36929351 dc identifier http //biodiversitylibrary org/page/36929351 smithsonian libraries Information field Flickr posted date ISOdate 2014-03-16 Check categories 2015 August 26 CC-BY-2 0 BioDivLibrary https //flickr com/photos/61021753 N02/13205249514 2015-08-26 12 55 49 cc-by-2 0 PD-old-70-1923 The Quarterly journal of the Geological Society of London 1883 Photos uploaded from Flickr by Fæ using a script | ||||
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