7 - 



the presentation of tetrapods as diphyletic. The comparison of details of the formation of the 

 ethmoid of these Rhipidistia is made basically with presently existing amphibians including very 

 specialized ones (for example, the frog) which creates great discrepancies in the i r. t eroret a * ion 

 of these details. At the same time, Jarvik's statements on the polyphyletic origin of tetrapods, 

 which in a series of cases are based on questionable facts are too categorical. 



--P. 1365- 



Wh i le there are no i nd 

 amphibians, a group of facts 

 great similarity in basic fe 

 seeming differences in i nd i v 

 ( Eusthop teron . Saur i pterus ?) 



isputable proofs in paleontology of the monophyletic origin of 

 does support it: 1. As indirect proofs one should include the 

 atures of the formation of the ethmoid of Rhipidistia in spite of the 

 idual representatives. 2. Among Rhipidistia or.ly Osteolep i formes 



have the formation of fins similar to the 

 biserial arch i pteryg ium (judging from the 

 hardly have been transformed into such a 

 mature Urodela and Eusthenopteron have an 

 to separate bones of the hand and foof. 

 given by the absence among known Rh i p i d i s 

 closely to the ancestors of the tetrapods 

 of the type Eusthenopteron and especially 

 little studied. 4. At the same time, kn 

 a dichotomous than a parallel development 

 according to Jarvik appear to the side of 

 and have an origin independent from fish- 

 the lower Cretaceous or 'Jurassic period ( 

 Lepospondyli which already flourished in 

 that Urodela branched oft precisely from 

 the same branch as labyrinthoden t s. On t 

 known, and they are encountered beginning 

 with labyr i nt hoden t s one can come to a co 

 not known in a fossil condition. [he app 

 seemingly by the end of the middle (Vorob 

 in the Silurian Period bony t i sh are stii 

 of lungfishes has been found, i.e., Porol 

 first Stegocephal ia are encountered, i.e. 



--f 

 forma 

 long- 

 highly 

 almos 

 3. So 

 t ia of 

 The 

 Pande 



own fi 

 of se 

 the m 



1 ike a 



fig. 7 

 the Ca 

 them. 

 he bas 



from 

 nclus i 

 earanc 



eva , 

 1 unkn 

 ep i s . 

 , the 



ig. 6-- 



t ion of a 



lobed f i ns 



different 



t identica 



me support 



groups wh 



closest t 



richthys ( 



nds of fos 

 parate bra 

 a i n line o 

 r ces tors o 

 ). In add 

 rbon i f erou 

 The Lepos 

 is of anc i 

 the Tr iass 

 on about t 

 e of the f 

 1962) or u 

 own and in 

 but at the 

 ich thyoste 



entadactyl limb (fig. 6). Fins with a 

 nt Holoptychus and Glyptolep i s) could 



n. In addition, the limbs of 

 1; this similarity extends even 

 if monophylet i c i sm can also be 

 ie recognized as standing 

 r, apparently only Osteolepifor 

 I962) unfortunately have been 

 ans testify in favor rather of 

 particular, Urodela, which 

 1 of terrestrial vertebrates 

 ■ian period, are unknown until 



are apparently ver/ close to 

 It is more logical to suppose 

 turn apparently derived from 

 the origin of Anura is well 



From the comparisoi of Anura 

 1 from the latter. Apoda are 

 iods has been indicated as 

 , 1964) Devonian Period since 

 Devonian Period only one genus 



upper Devonian Period the 



ted orga 

 forma t i 

 n favor 

 h could 

 the latt 

 rob ' eva, 

 1 amphib 

 hes. I n 

 evolut i 

 the Silu 

 ion, the 

 per i od. 

 ndyli in 

 t f : nds, 

 per i od. 

 ir or i g i 

 st tetra 

 er (Gros 

 he early 

 nd of th 

 ds. 



The ideal condition for the solution of the problem ot the origin of tetrapods would be 

 discoveries of intermediate forms between different groups ot vertebrates. The ecological 

 divergence which has existed since the very beginning of the emergence of tetrapoas and which has 

 been accompanied by significant morphological differences greatly hampers the clarification of 

 phylogene t ic 



--p. 1366-- 



links. For an understanding of the peculiarities and paths of the formation of the structures 

 ot tetrapods much could be gained through a study of lungfishes and especially of ancient 

 Rhipidistia. However, since using paleon tolog i cal discoveries as a base rarely permits a complete 

 restoration of the history of the origin of a group, one must consider the data 



-fig. 7" 

 of related disciplines. In particular, the study of contemporary amphibians and especially 

 embryolog ical investigations of the most primitive Urodela can be of considerable use for the 

 solution of this problem. 



A correct solution of the problem of the origin of terrestrial vertebrates is of great 

 importance for their taxonomy. The problem concerns not only by what kind of roots lungfishes 

 are connected with tetrapods, but also whether the existing system reflects phylogenetic links 

 between groups or whether it is based on the principles of similarity. The attempt to introduce 

 the concept of polyphyly into the existing system inevitably leads to the destruction of the 

 boundaries between taxonomic categories. In particular, if discussion cot cerns the polyphyletic 

 origin of amphibians, the continued existence of their independent phyletic branches destroys the 

 boundary between classes of fishes and amphibians. The diagnostics of the old classes loses its 

 value, and the dialect'cal representation of them as a new quality representing a complicated 

 complex 



-p. I367- 



