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Leedsichthys paper and news stories



From: Ben Creisler
bcreisler@gmail.com


A recent non-dino paper about the gigantic fish Leedsichthys and some
related news stories:


Jeff LISTON, Michael G. NEWBREY, Thomas James CHALLANDS and Colin E.
ADAMS (2013). Growth, age and size of the Jurassic pachycormid
Leedsichthys problematicus (Osteichthyes: Actinopterygii) : 145–175;
in ARRATIA, Gloria, Hans-Peter SCHULTZE & Mark V. H. WILSON (editors)
(2013): Mesozoic Fishes 5 – Global Diversity and Evolution:
Proceedings of the international meeting Saltillo, 2010:  560 pp.

Contents with pdfs:

http://www.pfeil-verlag.de/07pala/d4_59a.php

Leedsichthys pdf is free at:

http://www.pfeil-verlag.de/07pala/pdf/4_59d06.pdf


The Jurassic pachycormid osteichthyan Leedsichthys problematicus is
renowned for having been able to achieve prodigious size for a bony
fish. Building on work of MARTILL (1986a), a thorough examination of
all known material was conducted in order to constrain estimates of
the size of this animal and examine its rate of growth. Important
specimens of Leedsichthys are described for the first time. The
histology of Leedsichthys is reviewed, and the presence of growth
annuli is used to establish ages for five specimens. Age and growth
data were obtained from gill rakers (n=4) and lepidotrichia (n=2).
Lepidotrichia show upward curvilinear growth profiles and ages ranging
from 21 to 40 annuli, which are assumed to represent years. Both
growth profiles start at a small size (0.26 and 0.33 mm radial
distance), which is assumed to represent age 1. However, annuli can be
lost near the margins of the elements. Gill rakers exhibit a sigmoidal
growth profile. Age of gill rakers was estimated by adjusting the
alignment of the inflection points of the growth profiles thereby
giving adjusted ages. Gill rakers ranged in age from 19–38 annuli, but
all show evidence of reabsorption of annuli near the focal points and
at the margins of most elements. Sizes for the five individuals range
from 8.0–16.5 m for ages of 19–40 years. Growth rate (0.01–0.05 K) was
relatively slow as expected for a large, long-lived fish. At age 1,
individuals were 1.6 m in length. Estimates for the length of L.
problematicus compare well with published lengths of other large
suspension feeders such as those for basking and whale sharks.


News stories:

http://phys.org/news/2013-08-prehistoric-giant-fish-metres.html

http://o.canada.com/2013/08/26/canadian-fossil-expert-helps-identify-biggest-fish-ever-known/

http://www.heraldscotland.com/news/home-news/researchers-reveal-the-worlds-biggest-fish.21969545

http://www.theguardian.com/science/2013/aug/25/scale-jurassic-giant-fish-uncovered