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RE: Giant plankton-eating fish of the Mesozoic



Another potential impact on marine Cretaceous ecosystems is these
giant plankivorous fish would have represented an important food resource for 
mosasaurs, and the extinction of _Bonnerichthys_ and relatives at the K/Pg 
boundary could have contributed to mosasaur extinction, at least to the more 
hypercarnivorous taxa...
 
Guy Leahy
 
 

> Date: Sun, 28 Feb 2010 18:27:07 -0800
> From: tijawi@yahoo.com
> To: dinosaur@usc.edu
> CC: tijawi@yahoo.com
> Subject: Giant plankton-eating fish of the Mesozoic
> 
> Not directly dinosaur-related, but interesting nonetheless because of the 
> impact on marine Mesozoic ecosystems. A new paper in Science provides a 
> reason for why there are no unambiguous plankton-eating reptiles in the 
> Mesozoic: they were muscled out by big fishies. The following paper describes 
> two new genera of planktivorous fishes (_Rhinconichthys_ and 
> _Bonnerichthys_), part of a radiation of planktivorous stem teleosts 
> (Pachycormidae) that continued to the end of the Cretaceous.
> 
> 
> Although certain plesiosaurs have been described as "filter-feeders" (e.g., 
> _Aristonectes_, _Kaiwhekea_), with the small teeth and wide jaws used to 
> strain out small prey, it's my understanding that this is not true 
> "filter-feeding" (= suspension feeding). Instead, these plesiosaurs might 
> have had a feeding strategy more like the crab-eater seal, which has 
> sieve-like teeth for trapping krill.
> 
> 
> Friedman, M., Shimada, K., Martin, L.D., Everhart, M.J., Liston, J., Maltese, 
> A., and Triebold, M. 100-Million-Year Dynasty of Giant Planktivorous Bony 
> Fishes in the Mesozoic Seas. DOI: 10.1126/science.1184743 Science 327, 990 
> (2010).
> 
> "Large-bodied suspension feeders (planktivores), which include the most 
> massive animals to have ever lived, are conspicuously absent from Mesozoic 
> marine environments. The only clear representatives of this trophic guild in 
> the Mesozoic have been an enigmatic and apparently short-lived Jurassic group 
> of extinct pachycormid fishes. Here, we report several new examples of these 
> giant bony fishes from Asia, Europe, and North America. These fossils provide 
> the first detailed anatomical information on this poorly understood clade and 
> extend its range from the lower Middle Jurassic to the end of the Cretaceous, 
> showing that this group persisted for more than 100 million years. Modern 
> large-bodied, planktivorous vertebrates diversified after the extinction of 
> pachycormids at the Cretaceous-Paleogene boundary, which is consistent with 
> an opportunistic refilling of vacated ecospace."
> 
> 
> 
>