comment on this calibration


 node name
Tanaidacea     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations
Wolfe et al. 2016
  node minimum age
100.1 Ma
Amber inclusions bearing arthropod fossils were discovered from the Peñacerrada I outcrop, Basque-Cantabrian Basin, Álava, Spain(Alonso et al., 2000; Peñalver and Delclòs, 2010). The Peñacerrada I outcrop itself is divided into three intervals, with the lowest bearing the amber (Barrón et al., 2015). Earlier palynological study assigned Peñacerrada I to the Escucha Formation, in the late Aptian (Barrónet al., 2001). Recent restudy, however, amended this outcrop to the Utrillas Group (Barrón et al., 2015). The presence of marine palynomorphs characterized by Chichaouadinium vestitum and Palaeohystrichophora infusorioides, and the terrestrial Distaltriangulisporites mutabilis and Senectotetradites varireticulatus together constrain a late Albian age for the Peñacerrada I (Barrón et al.,2015). The upper boundary of the Albian stage is 100.5 Ma ± 0.4 Myr (Ogg et al., 2012a), providing a minimum estimate for Álava amber fossils at 100.1 Ma.
  node maximum age
521 Ma
A soft maximum age is obtained from the oldest mandibulate, Y. dianensis, which was recovered from the Yu'anshan Formation at Xiaotan section, Yongshan, Yunnan Province, attributed to the Eoredlichia–Wutingaspis Biozone (Zhang et al., 2007). Chinese Cambrian stratigraphy has been revised substantially and the Eoredlichia –Wutingaspis Biozone is no longer recognized (Peng, 2003, 2009). However, Eoredlichia is known to co-occur with Hupeidiscus, which is diagnostic of the Hupeidiscus-Sinodiscus Biozone, which is formally recognized as the second biozone of the Nangaoan Stage of the Qiandongian Series of the Cambrian of China (Peng and Babcock,2008). The Nangaoan is the proposed third stage of the Cambrian System for the International Geologic Timescale (Peng et al., 2012a).Thus, a soft maximum constraint can be established on the age of the lower boundary of the Nangaoan, which has been dated to 521 Ma (Peng et al., 2012a; Peng and Babcock, 2008).
 primary fossil used to date this node 
MCNA 9537
Alavatanais carabe, Vonk and Schram, 2007
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Peñacerrada I outcrop
     Stratum: Basque-Cantabrian Basin
     Geological age: Cretaceous, Mesozoic

More information in Fossilworks   PaleoBioDB

  phylogenetic justification
Spanish amber tanaids were originally misidentified as amphipods (Alonso et al., 2000). The fossils were placed in a new family, Alavatanaidae, part of the superfamily Paratanaoidea within Tanaidomorpha (Sánchez-García et al., 2015; Vonk and Schram, 2007). Characters supporting affinity within Tanaidomorpha include the presence of an articulated ischium, articulation of the last two pleopods (may be reduced in males), and seven or fewer antennal articles (Sánchez-García et al., 2015).
  phylogenetic reference(s)
Vonk, R., Schram, F.R., 2007. Three new tanaid species (Crustacea, Peracarida, Tanaidacea) from the Lower Cretaceous Alava amber in northern Spain. J. Paleontol. 81, 1502–1509.
Sánchez-García, A., Peñalver, E., Pérez-de la Fuente, R., Delclòs, X., 2015. A rich and diverse tanaidomorphan (Crustacea: Tanaidacea) assemblage associated with Early Cretaceous resin-producing forests in North Iberia: palaeobiological implications. J. Syst. Palaeontol. 13, 645–676.
 tree image (click image for full size) 
tree image
Figure 13 from Wofle et al. (2016).