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 node name
Holostei     Look for this name in NCBI   Wikipedia   Animal Diversity Web
  recommended citations Benton et al. 2015
  node minimum age
250 Ma
The Sakamena Group in Madagascar spans from late Permian to Middle Triassic, and the Middle Sakamena Group/ Formation is generally dated as lower Lower Triassic, the Upper Sakamena Group/ Formation, Lower to lower Middle Triassic. The entire Sakamena Group is some 4 km thick, and it is subdivided based on dominant lithologies: the middle portion is a sequence of shales and minot sandstones deposited in a logoonal or shallow lacustrine and braided river environment, whereas the units below and above are dominated by sandstones and conglomerates indicating higher energies of deposition. Dating of the Sakamena Group is notoriously difficult, as there are no radiometric dates, there has been no magnetostratigraphic study, and the associated fossils are not classic biostratigraphically useful index fossils. Nonetheless, the Middle Sakamena Group is dated as Induan on the basis of the associated fauna of benthosuchid temnospondyls (like those of the Lystrosaurus Assemblage Zone of South Africa and the Vokhmian units of Russia, as well as plants also suggesting Induan age. The top of the Induan stage is dated as ‘slightly older than’ 251.2 Ma ± 0.2 Myr (Mundil et al., 2010), and given as 250.01 Ma by Gradstein et al. (2012, p. 718), so we select this age as the minimum constraint, namely 250.0 Ma.
  node maximum age
331.1 Ma
Wastonulus represents the oldest definitive halecomorph, holostean, and crown neopterygian. This, combined with a rudimentary understanding of relationships among taxa in crownward portions of the neopterygian stem (including the so-called ‘subholosteans’), renders the formulation of a soft maximum age for crown Holostei difficult. The absence of many of the proximal outgroups of Holostei in pre-Triassic deposits might be taken as evidence for the rapid radiation of neopterygians and their immediate relatives following the Permo-Triassic extinction. However, the Permian record of ray-finned fishes is characterized by scarcity of deposits yielding well-preserved, articulated material (Hurley et al., 2007; Friedman and Sallan, 2012; Lloyd and Friedman, 2013; Sallan, 2014), suggesting this absence is more apparent than real. The Mississippian (Serpukhovian) Bear Gulch Lagerstätte in Montana, USA, includes a great diversity of articulated actinopterygians (Lund and Poplin, 1999), including taxa interpreted as crownward members of the neopterygian stem (e.g., Discoserra; Hurley et al., 2007; Xu et al., 2014). Holosteans or any other crown neopterygians are completely absent from this deposit. The base of the Serpukhovian is dated to 330.9 Ma ± 0.2 Myr, from which we derive a maximum age for crown Holostei of 331.1 Ma.
 primary fossil used to date this node 
MNHNFr MAE 33a,b
Watsonulus eugnathoides, Piveteau, 1935
Location relative to the calibrated node: Crown

[show fossil details]
     Locality: Sakamena Group, Ambilombe Bay
     Stratum: Middle Sakamena Formation
     Geological age: Triassic, Mesozoic

More information in Fossilworks   PaleoBioDB

  phylogenetic justification
Numerous cladistic analyses resolve Watsonulus as the sister group of all other halecomorphs (Gardiner et al., 1996; Grande and Bemis, 1998; Hurley et al., 2007; Grande, 2010; Friedman, 2012a; Arratia, 2013; Xu et al., 2014), and thus a member of the crown Neopterygii generally and crown Holostei specifically. This placement is supported by the derived presence of features shared by Watsonulus and other halecomorphs including a ‘double’ jaw joint involving the symplectic and a concave posterior margin of the maxilla (Grande and Bemis, 1998). In contrast to this current consensus, Olsen (1984) placed this genus as a stem neopterygian based on the retention of several primitive features not found in crown neopterygians. However, some of these features have not been detected in specimens by later researchers (e.g., an autogenous quadratojugal; Grande and Bemis, 1998), while others have a wider distribution within neopterygians than previously thought (e.g., presence of a clavicle in some stem teleosts; Arratia, 2013).
  phylogenetic reference(s)
Gardiner, B.G., Maisey, J.G. and Littlewood, D.T.J. 1996. Interrelationships of basal neopterygians, p. 117-146. In Stiassny, M.L.J., Parenti, L.R. and Johnson, G.D. (eds), Interrelationships of fishes. Academic Press, San Diego.
Grande, L. 2010. An empirical synthetic pattern study of gars (Lepisosteiformes) and closely related species, based mostly on skeletal anatomy. The resurrection of the Holostei. Amercan Society of Ichthyologists and Herpetologists Special Publication, 6:1-871.
Arratia, G. 1997. Basal teleosts and teleostean phylogeny. Palaeo Ichthyologica, 7:1-168.
Grande, L. and Bemis, W.E. 1998. A comprehensive phylogenetic study of amiid fishes (Amiidae) based on comparative skeletal anatomy: an empirical search for interconnected patterns of natural history. Society of Vertebrate Paleontology Memoir, 4:1-690.
Friedman, M. 2012. Parallel evolutionary trajectories underlie the origin of giant suspension-feeding whales and bony fishes. Proceedings of the Royal Society B, 279:944-951.
u, G.-H., Gao, K.-Q., and Finarelli, J.A. 2014. A revision of the Middle Triassic scanilepiform fish Fukangichthys longidorsalis from Xinjiang, China, with comments on the phylogeny of the Actinopteri. Journal of Vertebrate Paleontology.
 tree image (click image for full size) 
tree image
Figure 4 from Benton et al. (2014).