Rebuilding Bonnerichthys, a big fish from the Niobrara

Just like a model airplane kit,
Friedman et al. 2010 laid out the parts for the giant toothless Late Cretaceous Niobrara fish, Bonnerichthys gladius (Fig. 1).

The authors considered this big fish
to be a plankton eater from the get-go. The first sentence in their paper reads, “The largest vertebrates—fossil or living—are marine suspension feeders.” Bonnerichthys does have a big mouth and no teeth.

The authors also considered
Bonnerichthys to be a member of the Pachycormidae, of which Pachycormus is a tested taxon in the large reptile tree (LRT, 1649+ taxa).

Figure 1. Bonnerichthys parts from Friedman et al. 2010 and colorized here.

Figure 1. Bonnerichthys parts from Friedman et al. 2010 and colorized here. See figure 2 for a reconstruction.

Putting the parts back together
using DGS techniques (Fig. 2) Bonnerichthys took on the appearance of the extant arowana (Osteoglossum, Fig. 2 ghosted), a large, extant, tropical fish. Adapted to hunting at the surface, these ‘bony tongues’ are capable of leaving the water to catch prey on branches that overhang slow-moving rivers.

Figure 2. Reconstructed Bonnerichthys plus, at bottom and ghosted, Osteoglossum to scale.

Figure 2. Reconstructed Bonnerichthys plus, at bottom and ghosted, Osteoglossum to scale. These two taxa are a close match in all respects except time. Note the large pectoral fins on both.

Phylogenetic bracketing
indicates Bonnerichthys was a predator with its eyes on prey above the surface of the water, contra Friedman et al. 2010. Osteoglossum was not mentioned in their text, so this may be another case of taxon exclusion.

Figure x. Subset of the LRT focusing on basal vertebrates (= fish).

Figure x. Subset of the LRT focusing on basal vertebrates (= fish).

The post-crania of Bonnerichthys
was not presented, but should be distinct from Pachycormus when found.


References
Friedman M, Shimada K, Martin LD, Everhart MJ, Liston JJ, Maltese A and Triebold M 2010. 100-million-year dynasty of giant planktivorous bony fishes in the Mesozoic seas. Science 327(5968):990-993.

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