SVP abstracts 4: You heard it here first: a long-snouted marine osteoglossomorph

Capobianco and Friedman 2020 document
a long-snouted osteoglossid (primitive bony fish).

From the Capobianco and Friedman abstract:
“The fossil record of osteoglossid fishes (commonly known as bonytongues) includes several marine taxa found in early Paleogene deposits worldwide.”

By contrast, the LRT includes a Late Cretaceous (Fig. 1) and Late Jurassic (Fig. 2)  record of osteoglossid fish with an original radiation extending back to the Silurian based on chronological bracketing.

Figure 1. Protosphyraena museum mount. Length about 3m. Note the advanced placement of the pelvic fins.

Figure 1. Protosphyraena (Late Cretaceous) museum mount. Length about 3m. Note the advanced placement of the pelvic fins.

Figure 1. Aspidorhynchus overall. To the left, off screen, is the pterosaur, Rhamphorhynchus.

Figure 1. Aspidorhynchus (Late Jurassic) overall. To the left, off screen, is the pterosaur, Rhamphorhynchus.

Continuing the Capobianco and Friedman abstract:
“This is particularly remarkable as extant bonytongues are strictly freshwater and nest within a larger clade (Osteoglossomorpha) of freshwater fishes. Whether marine osteoglossids represent a clade descended from a single colonization of marine environments or a polyphyletic assemblage resulting from multiple independent marine invasions remains unclear.”

Adding the above taxa, both marine, should help resolve this issue.

“Here we describe a new species of osteoglossid from marine early Eocene (Ypresian) deposits of Morocco, represented by an articulated and three-dimensionally preserved skull with pectoral girdle. Besides displaying unique anatomical features such as an elongated preorbital region that likely reflects a peculiar feeding ecology among bonytongues, this specimen exhibits a tantalizing combination of characters shared with different extant osteoglossid subclades.”

Sounds similar to those taxa shown above, nesting within osteoglossomorpha here in June 2020 and here in February 2020.

“Phylogenetic analyses including the new taxon as well as other previously described marine bonytongues support a single marine invasion from a freshwater ancestor for Osteoglossidae.”

Only guessing here, but the authors likely omitted the above taxa.

“Moreover, some freshwater taxa – both extant and extinct – are recovered as nested within the marine radiation, suggesting that reverse transitions from the sea to riverine and lacustrine environments might have occurred multiple times during the early Paleogene.”

Sounds reasonable. 

Figure x. Subset of the LRT focusing on fish.

Figure 2. Subset of the LRT focusing on fish.

Continuing the Capobianco and Friedman abstract:
“Overall, the bonytongue fossil record indicates a remarkable first 20 million years of the Cenozoic for osteoglossids, with a diverse marine radiation after the K–Pg mass extinction and a complex biogeographical and ecological history including intercontinental dispersal and several major environmental transitions.”

Adding taxa will show the bonytongue fossil record will extend back to the Silurian due to chronological bracketing. In figure 2 the bony tongues are the second clade from the top in the yellow column, preceding all placoderms. Some basal forms were spiny sharks, with spiny pectoral fins similar to those in figures 1 and 2. Thus some spiny shark descendants are alive and well in modern Amazonian waters, while others are blog writers and readers.


References
Capobianco A and Friedman M 2020. A long-snouted marine bonytongue (Teleostei: Osteoglossidae) from the Early Eocene of Morocco: Glimpse into the under appreciated diversity of an Early Paleogene marine radiation of predatory fishes. SVP abstracts.

 

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