|
''Lectavis'' is a genus of enantiornithine birds. Their fossil bones have been recovered from the Late Cretaceous (Maastrichtian, c.70.6 - 66 mya) Lecho Formation at ''estancia'' El Brete, Argentina. The genus contains a single species, ''Lectavis bretincola''.〔 Etymology: "Lecho Formation bird living at El Brete". ''Lectavis'', after Latin ''lectus'' ("bed") = Spanish ''lecho'' + Latin ''avis'', "bird". ''bretincola'', after the type locality ''estancia'' El Brete + Latin ''incola'', "inhabitant".〕 The only known (this far) fossil bones (PVL-4021-1) are most of the left tibiotarsus (lower leg) and tarsometatarsus (upper foot) of a single individual. ''L. bretincola'' was a sizeable bird, with a 16-cm tibiotarsus and a tarsometatarsus which if complete must have been nearly 10 cm long (Chiappe 1993); this would make it roughly similar to a large curlew in size and at least in leg shape. It is most interesting in possessing a hypotarsus, which it evolved autapomorphically from modern birds, as it covers the upper end of the second, not the third toe's bones. This structure serves to attach and arrest the posterior cruciate ligament, which in turn prevents the lower and upper leg from shifting out of position during walking. Thus, it can be concluded that ''L. bretincola'' was a much more terrestrial species than its relative ''Yungavolucris brevipedalis'' which lived at the same time and place. Its habitat was a richly vegetated coastal area that was dotted by - possibly brackish - lakes and/or small rivers (Chiappe 1993), and it might thus be that the present species represents a case parallel evolution with waders and similar semi-aquatic forms, or even a running bird similar to an oversized courser, and quite unlike anything living today. It was a rather advanced species of enantiornithine and possibly quite closely related to ''Enantiornis'' and ''Avisaurus'', but more likely closer to other Euenantiornithes (Sanz ''et al.'' 1995). Its exact relationships, as with most enantiornithine birds, are unresolved however. ==References== * Chiappe, Luis M. (1993): Enantiornithine (Aves) Tarsometatarsi from the Cretaceous Lecho Formation of Northwestern Argentina. ''American Museum Novitates'' 3083: 1-27. (with Spanish abstract ) (PDF fulltext ) * Sanz, José L., Chiappe, Luis M. & Buscalioni, Angela D. (1995): The Osteology of ''Concornis lacustris'' (Aves: Enantiornithes) from the Lower Cretaceous of Spain and a Reexamination of its Phylogenetic Relationships. ''American Museum Novitates'' 3133: 1-23. (with Spanish abstract ) (PDF fulltext ) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lectavis」の詳細全文を読む スポンサード リンク
|