. Carnegie Institution of Washington publication. CHAPTER IV. THE MORPHOLOGY OF THE COAL MEASURES AMPHIBIA. The anatomy of the Coal Measures Amphibia presents many primitive types of structure. Their organization represents a stage passed through in the ontogeny of higher vertebrates. The animals are similar in a general way, yet so diverse are the modifications which they have suffered under different environmental conditions, that close scrutiny is needed to discern the exact relationship of the forms. Our knowledge of this relationship is based on the structures preserved, which are largely

- Image ID: RFRJAH
. Carnegie Institution of Washington publication. CHAPTER IV. THE MORPHOLOGY OF THE COAL MEASURES AMPHIBIA. The anatomy of the Coal Measures Amphibia presents many primitive types of structure. Their organization represents a stage passed through in the ontogeny of higher vertebrates. The animals are similar in a general way, yet so diverse are the modifications which they have suffered under different environmental conditions, that close scrutiny is needed to discern the exact relationship of the forms. Our knowledge of this relationship is based on the structures preserved, which are largely
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Image ID: RFRJAH
. Carnegie Institution of Washington publication. CHAPTER IV. THE MORPHOLOGY OF THE COAL MEASURES AMPHIBIA. The anatomy of the Coal Measures Amphibia presents many primitive types of structure. Their organization represents a stage passed through in the ontogeny of higher vertebrates. The animals are similar in a general way, yet so diverse are the modifications which they have suffered under different environmental conditions, that close scrutiny is needed to discern the exact relationship of the forms. Our knowledge of this relationship is based on the structures preserved, which are largely skeletal, since little is known of the soft anatomy (471) of the air-breathing vertebrates of the Coal Measures. The pubis is ossified in the Paleozoic Amphibia a.com. com info FIG. 6.—Generalized figure of dorsum of an early ampliil >ian skull to show position of elements and terminology adopted in this work. The outline is based on that of Eryops, but is in no way intended to indicate that form. a. com, anterior commissure of lateral-line canals; com, commissural communication between infra- and supra- orbital lateral-line canals; fr, frontal; inf, interfrontal; inn, internasal; info, infraorbital lateral-line canal; it, intertemporal; jl, jugal lateral-line canal; j, jugal; lar, lacrimal; mx, maxilla; n, nasal; oc, occiput; occ, occipital cross-commissure of the lateral-line system; or, orbit; par, parietal; pof, postfrental; pmx, premax- illa; pf, prefrental; po, postorbital; pp, postparietal; g, quadrate; gj, quadratojugal; spo, supraorbital lateral-line canal; sq, squamosal; spt, supra temporal; /, temporal lateral-line canal; tab, tabulare. later than the ischium and ilium; the carpus and tarsus are cartilaginous; the verte- brae consist of a pleurocentrum and two neurocentra, thus paralleling conditions in modern mammalian embryos. (a) The skull of the Coal Measures Amphibia has (fig. 6) essentially the same structure in the different groups. It is largely formed

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