Dobrogeria aegyssensis, a new early Spathian (Early Triassic) coelacanth from North Dobrogea (Romania)

Abstract

ABSTRACT:Cavin, L. and Grădinaru, E. 2014. Dobrogeria aegyssensis, a new early Spathian (Early Triassic) coelacanth from North Dobrogea (Romania). Acta Geologica Polonica, 64 (2), 161-187. Warszawa.The Early Triassic witnessed the highest taxic diversity of coelacanths (or Actinistia), a clade with a single living genus today. This peak of diversity is accentuated here with the description of a new coelacanth discovered in the lower Spathian (Upper Olenekian, Lower Triassic) cropping out in the Tulcea Veche (Old Tulcea) promontory, in the city of Tulcea, in North Dobrogea, Romania. The bone remains were preserved in a block of limestone, which was chemically dissolved. The resulting 3D and matrix-free ossifications correspond mostly to elements of the skull and branchial apparatus. Posterior parietals, postparietal with associated prootic and basisphenoid allow a precise description of the neurocranium. Ossifications of the lower jaw, together with branchial and pectoral elements, complete the description of this coelacanth and support the coining of a new generic and specific name, Dobrogeria aegyssensis. A phylogenetic analysis of actinistians with the new species recovers clades which were found in most recent analyses, i.e. the Sasseniidae, the Laugiidae, the Coelacanthiformes, the Latimerioidei, the Mawsoniidae and the Latimeriidae, and identifies the new taxon as a non-latimerioid coelacanthiform.

Microvertebrates from the classic Rhaetian bone beds of Manor Farm Quarry, near Aust (Bristol, UK)

“…6). These bones are rod-like, flaring at the base into a double articulation, with a distinctive grooved articulatory surface; this double glenoid for articulation with the lower jaw is typical of coelacanths (Cavin and Grădinaru, 2014). The rod-like, central shaft portion in some specimens forms a broader flange.…”

A new fossil actinistian from the Early Jurassic of Chile and its bearing on the phylogeny of Actinistia

“…Wendruff and Wilson (2012) included only one representative of the Whiteiidae, Whiteia, in their analysis. Cavin et al (2013) and Cavin and Gr adinaru (2014) included five whiteiid genera (plus the new studied fossil form), whereas Wen et al (2013) considered only three whiteiid genera (plus the two new studied fossil taxa). The whiteiids were placed either in a polytomy with other genera (Cavin et al, 2013) Arratia and Schultze-A new Early Jurassic actinistian from Chile (e983524-10) Gr adinaru, 2014).…”

“…The content of the Mawsoniidae and Latimeriidae is the same in Cavin et al (2013) and Cavin and Gr adinaru (2014), and few Triassic genera are included above Latimeria in both analyses. Those are different results from the ones presented here.…”

A mawsoniid coelacanth (Sarcopterygii: Actinistia) from the Rhaetian (Upper Triassic) of the Peygros quarry, Le Thoronet (Var, southeastern France)

“…In particular, the short dorsum sella and the well-defined sphenoid condyles separated by a small depression are characters present in the basal mawsoniids Chinlea and Diplurus (Schaeffer, 1967), and in the derived mawsoniids Mawsonia and Axelrodichthys (Maisey, 1986; Carvalho & Maisey, 2008). In non-mawsoniid coelacanths, for instance Latimeria, Megalocoelacanthus or Dobrogeria , when visible the sphenoid condyles are less marked and separated by a wider gap (Forey, 1998; Dutel et al 2012; Cavin & Grădinaru, 2014). Recently, the Early Jurassic Trachymetopon liassicum was included in the mawsoniids by Dutel, Herbin & Clément (2015).…”