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Sparalepis tingi by Gogosardina Sparalepis tingi by Gogosardina
2012 & 2016. acrylics on card, digital & photography.

c. 423,000,000 bp, late Silurian (Ludlow), Qujing, Yunnan, China.

Artwork specially created for = 
Brian Choo; Min Zhu; Qingming Qu; Xiaobo Yu; Liantao Jia; Wenjin Zhao (2017). "A new osteichthyan from the late Silurian of Yunnan, China". PLOS ONE12 (3): e0170929. doi:10.1371/journal.pone.0170929.

Introducing another odd fish from the Silurian Kuanti Formation of Yunnan, the only pre-Devonian site in the world to produce well preserved fossil gnathostomes. This is Sparalepis tingi swimming in the foreground along with two other fish I had a hand in describing: a pair of the maxillate placoderm Entelognathus in the middle distance and two big predatory Megamastax in the distance (greatly revised from my earlier reconstruction based on new fossil material). Conodont animals swarm around them.

Sparalepis is known from a single exquisite fossil representing much of the postcranium of a fish about 20 cm long. This is only the second Silurian bony fish based on more than isolated fragments. It is possible that we have parts of the head of Spara in the IVPP collections, but it is hard to be certain without overlapping elements (the head bits clearly represent many new osteichthyan taxa). The name is a combination of ancient Persian and Greek, meaning "shield scale". The rectangular scales reminded me of depictions of the wicker shields carried by the Sparabara heavy infantry of the Achaemenid Empire.

The new fish is a cousin of Guiyu, another Kuanti fish, along with the slightly more recent Psarolepis. These very ancient bony fish share a host of characters with the extinct placoderms, including spine-bearing dermal pectoral and pelvic girdles and large median dorsal plates. Our discovery lends weight to
 the hypothesis that the ancestral gnathostomes possessed a placoderm-like bodyplan. These three genera, plus Achoania, *might* form a clade of stem-sarcopterygians ("Psarolepids") although I suspect that most of the characters uniting them in the available datasets will turn out to be osteichthyan symplesiomorphies (archaic "default settings" retained from the common ancestor of all bony vertebrates).

Sparalepis has unusual scales, being particularly (dorsoventrally) tall, (anteroposteriorly) narrow and (mediolaterally) thick. The ones at the front are really weird - most early bony fish have a peg-and-socket articulation on the basal surface of dorsal pegs that slot into ventral sockets of the scale above them. Spara also has these, but in addition to a complimentary system on the outer scale surface =  dorsal "sockets" and ventral "pegs" (ventral bulges of the ornamented free field). The front end of the fish must have been very stiff, with limited mobility.

The new discovery adds to a growing list of Kuanti fishes, revealing a Silurian fauna where jawed vertebrates displayed exceptional diversity and anatomical innovation, long before the Devonian "Age of Fishes". 

Add a Comment:
 
:iconindigomagpie:
indigomagpie Featured By Owner 2 days ago
What happened to the theory that conodont animals were actually mud-burrowing and the "eyes" were actually lumps of cartilage to anchor the conodont apparatus?
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:icongogosardina:
Gogosardina Featured By Owner 2 days ago  Professional Traditional Artist
One paper back in the 90s (I think it was Pridmore et al. 1997, need read it again) dismissed conodont eyes, but given we have the structures preserved in multiple conodont taxa, the overall consensus is, yes they are eyes.

With regards to a purely burrowing lifestyle. The sheer abundance and diversity of conodont elements in the Gogo Formation (Late Devonian Western Australia) would seem to argue against this since:

A) The sediments formed in deep anoxic inter-reef basins. 

Would have been a hostile environment for any chordate, or at least a biozone unlikely to support such a huge biomass of chordates. Makes more sense that the preserved conodonts are the remnants of free-swimming animals from the better oxygenated reef areas whose bodies sank into the depths (as with the fish fossils). If they were burrowers in shallow waters, you wouldn't expect their fossils to be so abundant in the deep sediments.

B) entire conodont apparatuses are preserved as gut contents of presumably mid-water predatory fishes (especially actinopterygians).
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:iconindigomagpie:
indigomagpie Featured By Owner 2 days ago
Oh good - I always liked the cute ones :-)
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:icon105697:
105697 Featured By Owner Mar 15, 2017
Awesome. I just heard of this guy today.

W+Just wondering, what was the fossil material that made your old reconstruction of Megamastax inaccurate? What does the new reconstruction have that makes the old one innacurate?
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:icongogosardina:
Gogosardina Featured By Owner Mar 16, 2017  Professional Traditional Artist
smaller eyes, smaller scales, no median dorsal plate behind the skull... 
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:icon105697:
105697 Featured By Owner Mar 16, 2017
ah okay.
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:iconcoloiid:
Coloiid Featured By Owner Mar 12, 2017  New Deviant Student Traditional Artist
It looks so lifelike! Hopefully I'll be able to get one >3<
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:iconzimices:
Zimices Featured By Owner Mar 9, 2017  Hobbyist
Exceptional finding and restoration! :)
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:iconsaberrex:
Saberrex Featured By Owner Mar 9, 2017  Hobbyist General Artist
That's such a cool find. I guess the real diversity jaws started earlier than I thought.
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March 9
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