Fig 1.
Cellicalichnus krausei isp. nov. preserved in a paleosol from the Castillo Formation in Tronador canyon (Argentina).
(A) The first specimen found (MPEF-IC 4602, paratype). Scale bar = 2.5 cm. (B) The longest specimen (MPEF-IC 4600, holotype). Scale bar = 2.5 cm.
Fig 2.
Geographic position and sedimentologic profiles.
(A) Location of the studied sites in Argentina. (B) Chubut province. (C) Outcrops of the Cretaceous Chubut Group (green) in the southwest of Chubut. Red stars indicate the two studied sites of the Castillo Formation. (D) Measured sections of the Albian Castillo Formation in the Tronador canyon, north sector of the San Jorge basin. Details of paleosols (P) are shown. The black star indicates the position of the radiometric date presented herein.
Fig 3.
Type material and the most complete specimens of Cellicalichnus krausei isp. nov.
(A) Holotype (MPEF-IC 4600). (B) Paratype (MPEF-IC 4601). (C) Fragment of a nest showing a lateral tunnel at a right angle (arrow, MPEF-IC 4625). (D) Fragment of a nest showing cells and scars (MPEF-IC 4610). Note the sessile cells in all cases. Scale bars are 5 cm.
Fig 4.
Other insect trace fossils found along with the bee nests in the Castillo Formation.
Fictovichnus sciuttoi (A–D). (A) Lateral view of a specimen showing the flattened outline (MPEF-IC 4669). (B) Specimen preserving a helical surface morphology composed of fine ridges (arrow, MPEF-IC 4698). (C) Specimen showing rough ridges (arrow, MPEF-IC 4700). (D) Specimen with a flat oval area in one extreme (arrow, MPEF-IC 4683). Pallisphaera puertai isp. nov.(E–H). (E) Holotype in the matrix showing the casts of pellets (arrow, MPEF-IC 4712). (F) Paratype in the matrix showing the casts of pellets (arrow, MPEF-IC 4713). (G) Wall of a specimen attached to the matrix (MPEF-IC 4725). Note the pellets (arrow). (H) Specimen with an emergence hole (arrow, MPEF-IC 4718). Pallisphaera piriforme isp. nov. (I–K). (I) Holotype showing pellets and the lateral protuberance (MPEF-IC 4732). Note the piriform shape and the tight constriction between the two spheroids (arrow). (J) Ovoid specimen (MPEF-IC 4734, paratype). (K) Longitudinal section of a specimen showing cylindrical pellets (arrows, MPEF-IC 4824). Scale bars are 10 mm.
Fig 5.
Maximum clade credibility tree obtained from all data.
Numbers on the phylogram indicate node ages in Ma. Asterisks on nodes indicate posterior bayesian probabilities >0.9. Calibration points are shown as stars on nodes of groups that they cluster: red stars are trace fossils and yellow stars are body fossils. The latter were already used in previous analyses (except the calibration for root node). Grey area from root to about 95 Ma indicates the Early Cretaceous fast cladogenesis of most bees (this study) and Eudicots [44]. Circled numbers indicate the following taxa: 1-Stenotritidae; 2-Megachilidae; 3-Apidae; 4-Rophitinae; 5-Nomiinae; 6-Halictini; 7-Augochlorini; 8-Caenohalictini (6+7+8+Sphecodini = Halictinae); 9-Scrapterinae; 10-Xeromelissinae; 11-Euryglossinae; 12-Hylaeinae; 13-Diphaglossinae; 14-Neopasiphaeinae.