Palaxius caracuraensis Kietzmann, 2010
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publication ID |
https://doi.org/ 10.4202/app.2009.0094 |
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persistent identifier |
https://treatment.plazi.org/id/A2018795-2140-FFB2-FCEE-F897926BFBBC |
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treatment provided by |
Felipe |
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scientific name |
Palaxius caracuraensis Kietzmann |
| status |
sp. nov. |
Palaxius caracuraensis Kietzmann isp. nov.
Fig. 2B View Fig .
Etymology: After the Cara Cura range, where the new ichnospecies was found.
Holotype: The specimen illustrated in Fig. 2B View Fig , thin section CPBA−N ° 20689.
doi: 10.4202/app.2009.0094
Type locality: La Tosca creek , Cara Cura range, Mendoza province, Argentina (36 ° 40'12.28''S, 69 ° 40'13.21''W) GoogleMaps .
Type horizon: Vaca Muerta Formation, Substeueroceras koeneni Zone , 170 m from the base.
Diagnosis.—Species of the genus Palaxius with ten canals clustered around a symmetry plane (2−3:3−2). It differs from comparable ichnospecies ( P. habanensis Brönnimann and Norton, 1960 and P. decaochetarius Palik, 1965 ) in the orientation of canals 1 and 2 in respect to the center of the coprolite, and the different morphology of canals 4 and 5 ( Fig. 2B View Fig ).
Material.— Six specimens from thin section CPBA−N ° 20689 and nine specimens from thin section CCPBA−N ° 20690, 20691, 20692.
Description.—Microcoprolite with circular to oval cross section. The holotype has a diameter of 1,300 µm in cross section parallel to the symmetry plane and 1,800 µm perpendicularly to it. Internally, it shows ten canals arranged in two bilaterally symmetric groups of five canals (2−3:3−2). Each group consists of two “dorsal” canals (canals 1 and 2) and three “ventral” canals (3/3', 4/4' and 5/5'). Observed perpendicularly to the symmetry plane, canals 1/1' and 2/2' are crescent shaped and their concave sides face the symmetry plane, canal 3/3' is sickle shaped with its concave side towards the symmetry plane, while canals 4/4' and 5/5' are sickle shaped and their convex sides face the symmetry plane. Canals are 250 µm long and 60–80 µm wide. Their extremities show rounded protuberances. Canal 1/1' is orientated at 20 ° from the bilateral symmetry plane; canals 2/2' and 4/4' are at 45 °; canal 3/3' is at 120 °, and canal 5/5' is at 90 °. In none of our specimens was a ventral groove observed. Comparisons.—Other five ichnospecies with ten canals are known ( Fig. 3 View Fig ). The new ichnospecies presents similarities with P. habanensis and P. decaochetarius . It is differentiated from P. habanensis by the direction of canals 1/1' and 2/2', as well as by the morphology of canals 4/4' and 5/5', which are crescent shaped in P. habanensis and sickle shaped in P. caracuraensis Kietzmann isp. nov. It differs from P. decaochetarius in the morphology of canals 4/4' and 5/5' which are crescent shaped in P. decaochetarius , and also in size and width of the canals.
Stratigraphic and geographic range.—The new ichnospecies was recognised in levels corresponding to the Corongoceras alternans (lower late Tithonian) and Substeueroceras koeneni (upper late Tithonian–early Berriasian) zones, in the Cara Cura range section, Vaca Muerta Formation ( Fig. 1 View Fig ). Similar but poorly preserved microcoprolites were documented in the same levels but in the Loncoche creek, Chihuido slope, and Yeso creek sections.
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