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Salientia - Bufonidae
If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|R. Estes and R. Wassersug 1963||"Tihen (1962a, p. 163) defines the valliceps species group of Bufo as follows: frontoparietals broad, usually produced into crests; roofing bones ornamented; occipital groove enclosed to form a canal; frontoparietals and prootics fused. He then divides valliceps group into three essentially geographical subgroups: the Mexican section in Central and North America; the South American section in South and Central America; and the Caribbean section, throughout the Neotropical Region, <|
The fossil is placed in the valliceps group on the basis of presence os all of the above characters. Within this group, it is eliminated from the Mexican section by having a strong overlap of the medial wings of the pterygoids onto the wings of the parashenoid and complete closure of the suprapterygoid fenestra (ibid., p168). The strongly-overlapping pterygoids are characteristic of the South American section, and do not usually occur in the Caribbean section, but the occluded suprapterygoid fenestra is present in the latter (ibid., p. 171). This single resemblance to the members of the Caribbean section will be discussed below.
Bufo chilensis of the South America section and B. retiformis of the Caribbean section were the only species not available for this study. The dermal ornamentation of the fossil is most like that of the South American section, which has crests of only moderate extent and development and a lined or wrinkled sculpture; while crests in members of the Caribbean section are often extensive, exaggerated, and the sculpture is pustular.
A final factor used in allocating the fossil to the South American section was the width of the vertebra centra, which are perceptibly narrower in portion to their length in the Caribbean group. As might be expected, the results are correlated with size, so that only specimens of the Mexican section resemble the Caribbean forms in also having the narrow centrum.
The above considerations indicate that the fossil belongs to the South American section, but it differs from these forms in one characteristic of importance to Tihen's classification. He indicates (ibid., pp. 165-166) that the suprapterygoid fenestra is not markedly occluded in the South American section of the valliceps group, while it is often nearly closed by flanges of pterygoid and squmosala in members of the Caribbean section. The fenestra is completely closed in the fossil, thus indicating a possible relationship to the latter group in terms of the classification based on skeletons of Recent species. However, the suprapterygoid fenestra, as a taxonomic character, may be weak in some cases (as Tihen realized), owing to its qualitative nature. Tihen points out (ibid., p. 174) that B. typhonius of the Caribbean section lacks an occluded suprapterygoid fenerstra. One specimen of B. peltocephalus of the Caribbean section (M.C.Z. no 23564) also has an open fenestra. Within the South American section, one specimen of B. paracnemis (M.C.Z. no. 343) has the fenestra closed on one side of the skull. It is possible that closure of the fenestra in Recent specimens may be both variable within the species as a whole, and be partly a function of age of the specimen. In addition, since there has been a trend in many groups (including anurans) toward deossification, geologic age can be a modifying factor as well. The latter is probably the most important with respect to this fossil, since a number of regions, e.g. shoulder girdle (see above) and prootic show a greater amount of ossification than comparable regions in any Recent specimen of either New or Old World Bufo seen by us.
The crista medialis of the humerus is of some interest in this specimen, because it is a secondary sexual characteristic in some Recent frogs. The crista forms the attachment for the M. flexor carpi radialis, which aids in flexing the wrist and is important in amplexus. Ecker (1889, pp. 42-43) indicated that the crista was present in males of Rana esculenta, R. temporaria, and R. oxyrhinus. Holmes (1924, p. 241), in discussing the same species, states that it is present in both males and females, but is more prominent in males. Inasmuch as the methods of embrace and courtship are more or less uniform throughout the Salientia (Noble, 1931, p. 111), this characteristic may be of similar significance in other anurans as well."
"Only a small number of the M.C.Z. collection of New World Bufo were sexed at the time of skeletonization, and of the others, only a few have the ridge to any great extent. B. marinus horribilis (M.C.Z. no. 29028), a male which lacks the crista medialis, was the smallest individual of that species in the osteological collection and may not have reached maturity, The fossil is thus most probably a male, though exceptions such as the above render this uncertain." (...) "We have followed Tihen's taxonomy (1962a) for convenience in discussion." (...) "Hence the strongest resemblance between the fossil and any Recent group, on the basis of the available specimens, is with Bufo marinus marinus. The tendency toward obliteration of sutures, the relatively greater ossification in prootics, suprapterygoid fenestra, and shoulder girdle, as well as the general robustness of some of the bones themselves, do not, in our opinion, warrant nomenclatorial recognition at the specific level, but merely reflect the often greater ossification seen in many fossils (discussed above on p. 9) and probably indicates a stage in the evolution of Bufo marinus in the broad sense. In identifying this specimen with the Recent Bufo marinus, we realize, with Taylor and Smith (1945, p. 541) and Savage (1960, p. 235) that the concept of B. marinus as currently used is a broad one, yet further refinement in the assessment of relationships of this fossil cannot precede re-evaluation of the Recent Bufo marinus complex."
"A late Miocene toad from the upper Magdalena Valley, Huila, Colombia, South America, is referred to the Recent species Bufo marinus. Within this poorly understood group, it seems to show closest resemblance to B. m. marinus from northern South America. It differs from B. marinus only in having slightly greater
ossification in the suprapterygoid fenestra, lateral parts of the prootics, and glenoid region of the shoulder girdle. This condition is insufficient evidence for recognizing a taxonomie difference from B. marinus, at least until restudy of the Recent forms is effected. The broad geographic and altitudinal range of the Recent species precludes ecologic interpretation. The Species is aquatic, and common today along large river courses and may have been so on the Miocene floodplains as well. The fossil, in combination with the lizards described by Estes (1961), is another indication of the modernity of the herpetological elements of the late Miocene La Venta fauna, and of the greater extent of the floodplain—aquatic habitat in northern South America during the late Miocene."