Strange Squaloraja has a new sister in the LRT: Scapanorhynchus

Earlier one of the the strangest of all bottom-dwelling vertebrates,
Squaloraja (Fig. 1), nested in the LRT with paddlefish (= Polyodon) and goblin sharks (= Mitsukurina), rather than the traditional ratfish (= Chimaera).

Figure 1. Squaloraja is not the chimaerid everyone thinks it is, but nests with Scapanorhynchus and Mitsukurina in the paddlefish clade.

Figure 1. Squaloraja is not the chimaerid everyone thinks it is, but nests with Scapanorhynchus and Mitsukurina in the paddlefish clade.

Today
a traditional relative of Mitsukurina, Scapanorhynchus (Davis 1887, Woodward 1889, 1899; Figs. 2, 3) nests closer to Squaloraja (Fig. 1) in the paddlefish clade.

Figure 2. Skull of Scapanorhynchus traced and reconstructed using DGS.

Figure 2. Skull of Scapanorhynchus traced and reconstructed using DGS. Note the large eyes as in Squaloraja.

Scapanorhynchus lewisii
(originally Rhinognathus lewisii David 1887; Woodward 1889; NHMUK PV P 4774; Early Cretaceous; 65cm to 1m in length) is widely considered a relative of Mitsukurina, the goblin shark, but here nests closer to Squaloraja. Here the gill basket is much longer, the eyes are midway in size and two dorsal fins are retained.

FIgure 3. Scapanorhynchus, and Early Cretacous goblin shark.

Figure 3. Scapanorhynchus, and Early Cretacous goblin shark.

Squaloraja polyspondyla (Agassiz 1843, Woodward 1866, Early Jurassic) is traditionally considered a relative of Chimaera, but here nests with Scapanorhynchus from the Cretaceous.

Figure 6. Adding Debeerius to the LRT helped revise the shark-subset. Note the shifting of the basking shark, Cetorhnus within the paddlefish clade.

Figure 4. Adding Debeerius to the LRT helped revise the shark-subset. Note the shifting of the basking shark, Cetorhnus within the paddlefish clade.

This appears to be
another  novel hypothesis of interrelationships. If not, please supply the citation so I can promote it.


References
Agassiz L 1843. Recherches sur les Poissons Fossiles, III (IV), Imprimerie de Petitpierre, Neuchatel, pp. 157-390.
Davis JW 1887. The fossil fishes of the chalk of Mount Lebanon, in Syria. Scientific Transactions of the Royal Dublin Society, 2 (3): 457–636, pl. 14–38.
Woodward AS 1886. On the anatomy and systematic position of the Liassic selachian Squaloraja polyspondyla Agassiz. Proceedings of the Zoological Society of London, 1886: 527–538.
Woodward AS 1889. Catalogue of the Fossil Fishes in the British Museum. Part 1. London: British Museum of Natural History, 1-474.
Woodward AS 1899. Note on Scapanorhynchus, a Cretaceous shark apparently surviving in Japanese seas. Annals and Magazine of Natural History, (Series 7), 3 (18): 487–489.

Other references online here and here.

wiki/Squaloraja
wiki/Scapanorhynchus

 

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