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Millerocaulis (Erasmus) ex Tidwell (Osmundales, Filices) from the Carrrizal Formation (Upper Triassic) from Marayes, San Juan province, Argentina

2006; Museo Argentino de Ciencias Naturales Bernardino Rivadavia e Instituto Nacional de Investigación de las Ciencias Naturales; Volume: 8; Linguagem: Inglês

10.22179/revmacn.8.318

1853-0400

Rafael Herbst,

Paleontology and Evolutionary Biology

Millerocaulis (Erasmus) ex Tidwell (Osmundales, Filices) from the Carrrizal Formation (Upper Triassic) from Marayes, San Juan province, Argentina. Based on newly found specimens, «Marayea lutzi» Herbst 1994, of the Upper Triassic Carrizal Formation, from Marayes (San Juan province , Argentina) is analyzed. Anatomical characters, specially those from the central cylinder, now defines the species as an ectophloicdictyoxylic siphonostele (sensu Miller) and shows that it must be changed to Millerocaulis. Thus, Marayea defined as a siphonostelic genus becomes invalid and an emended diagnosis for the type species is given. Also, from the same locality and age other, rather big specimens, are described. They are not well preserved but the available characters allow to incorporate them as Millerocaulis sp. These two species and others formerly described of this genus, M. herbsti (Archangelsky & de la Sota) Tidwell and M. stipabonettii Herbst, from the Laguna Colorada Formation (Santa Cruz province) and Cepeda Formation (San Juan province) respectively from Argentina along with M. beardmorensis Schopf and Ashicaulis woolfei Rothwell, Taylor & Taylor, from the Fremouw Formation (Antarctica) and the frond Osmunda claytoniites Phipps et. al.,as well as some petioles lacking cellular structure but undoubtely belonging to Millerocaulis, from the Los Rastros Formation (San Juan province), all from the upper Middle to Upper Triassic, show the diversification of the Osmundales as early as this time span, at least in this part of Gondwana