Coniferous wood ofAgathoxylonfrom the La Matilde Formation, (Middle Jurassic), Santa Cruz, Argentina

Abstract

In this contribution, four species of Agathoxylon are described from the La Matilde Formation, Gran Bajo de San Julián and central and south-western sectors of Santa Cruz Province, Argentina. Agathoxylon agathioides (Kräusel and Jain) n. comb., Agathoxylon santalense (Sah and Jain) n. comb., Agathoxylon termieri (Attims) Gnaedinger and Herbst, and the new species Agathoxylon santacruzense n. sp. are described based on a detailed description of the secondary xylem. In this work, it was possible to construct scatter plots to elucidate the anatomical differences between the fossil species described on quantitative anatomical data. Comparisons are made with other Agathoxylon species from Gondwana. These parameters can be used to discriminate genera and species of wood found in the same formation, as well as to establish differences/similarities between other taxa described in other formations. Some localities contain innumerable “in situ” petrified trees, which allowed us to infer that these taxa formed small forests, or local forests, or small forests within a dense forest, which is a habitat coincident with the extant Araucariaceae.

Agathoxylon santacruzense Kloster & Gnaedinger from the Lower–Middle Jurassic Kota Formation, India and its paleoenvironmental implications

“…Upper Gondwana Jurassic sediments of La Matilde Formation, Santa Cruz Province, Argentina (Kloster & Gnaedinger, 2018). The description of the material in the present study agrees with that of A. santacruzense in many characters, such as number of cross-field pits, ray height in number, and type of bordered pits on radial walls.…”

“…However, the recent discovery of fossil fauna strongly suggested Lower to Middle age connotation such as the Early to Middle Jurassic (Parmar et al, 2013). The present finding of fossil wood belonging to Agathoxylon santacruzense, species originally described from the Middle Jurassic La Matilde Formation, Santa Cruz Province, Argentina (Kloster & Gnaedinger, 2018) also favors the restricted age connotation. However, it is possible that the age considered here for the Kota Formation would be subjected to modification as we get more and more information in the future.…”

Coniferous woods from the Upper Triassic of southwestern Gondwana, Tronquimalal Group, Neuquén Basin, Mendoza Province, Argentina

“…From comparisons made with most fossil species of the genera Araucarioxylon , Dadoxylon , and Agathoxylon , the diagnostic characters of the Chihuido and Llantenes specimens allow their assignment to Agathoxylon lamaibandianus (Gnaedinger et al, 2015; Kloster and Gnaedinger, 2018). This species has been characterized by araucarian wood with uniseriate to biseriate, alternate, circular, and flattened tracheid radial pitting, rays of 3–23 cells in height, cross-fields with one to four cupressoid pits arranged in araucarioid pattern (Crisafulli and Herbst, 2011).…”

Permineralized conifer-like leaves from the Jurassic of Patagonia (Argentina) and its paleoenvironmental implications

“…this article was supported by funds ANPCyt PICt 2012/528, CONICEt PIP 112-201201-00212 granted to GMDF; SGCyt-UNNE. PI 2015-2018, Q005-2014, CONICEt PIP 2014-2016 201301 00317 granted to SCG and ANPCyt PICt 2015/2206 granted to MAC.…”

“…the outcrops of the La Matilde Formation at the Gran Bajo de San Julián area contain a rich and diverse petrified plant assemblage that includes stems of Millerocaulis and Osmundacaulis of the Osmundales (herbst 2001, 2003) and trunks of Ginkgomyeloxylon of the Ginkgoales (Gnaedinger 2012) and of several conifers. Within this last group, the Podocarpaceae is well-represented by Podocarpoxylon, Circoporoxylon and Circoporopitys (Gnaedinger 2007a), whereas the Araucariaceae are represented by several species of Agathoxylon (Kloster and Gnaedinger 2018), the Cupressaceae by Protelicoxylon and Herbstiloxylon (Gnaedinger 2007b), and the taxaceae by Prototaxoxylon (Gnaedinger and herbst 2006).…”