Saurichthys
Name:
Saurichthys
(Lizard fish).
Phonetic: Sore-ick-fiss.
Named By: Louis Agassiz - 1834.
Synonyms: Belonorhynchus,
Brevisaurichthys, Giffonus, Ichthyorhynchus, Systolichthys.
Classification: Chordata, Actinopterygii,
Saurichthyiformes, Saurichthyidae.
Species: S. apicalis (type),S.
aculeatus, S.
annulatus, S. breviabdominalis, S. calcaratus, S. catalaunicus, S.
curionii, S. daubreei, S. dawaziensis, S. deperditus, S. dianneae, S.
dongusensis, S. eximius, S. gigas, S. gracilis, S. grignae, S.
gypsophilus, S. hamiltoni, S. hoffmanni, S. huanshenensis, S. indicus,
S. irregularis, S. latifrons, S. lepidosteoides, S. listroconus, S.
longiconus, S. longidens, S. macrocephalus, S. majiashanensis, S.
minimahleri, S. nepalensis, S. obrutchevi, S. orientalis, S. osseus, S.
parvidens, S. piveteaui, S. proximus, S. rieppeli, S. sceltrichensis,
S. seefeldensis, S.
semicostatus, S. spinosa, S. stensioi, S. striatulus, S. striolatus, S.
subulatus, S. tenuirostris, S. tertius, S. ultimus, S. vjuschkovi, S.
yangjuanensis, S. yunnanensis
.
Diet: Carnivore/Piscivore.
Size: Between 0.6 and 1.5 meters long depending upon
the species.
Known locations: Worldwide.
Time period: Triassic.
Fossil representation: Multiple specimens.
As
an early ray finned fish Saurichthys displays several characteristics
of a fast swimming predator, however the exact method of hunting is
still not known for certain. The caudal (tail) fin was not as
well developed as other open water fish, although the close proximity
of the dorsal (back) and anal (bottom) fins set much further
back on the body would have had a contributing effect of providing
additional thrust as Saurichthys flexed its tail from side to side.
Additionally the long torpedo-like body meant that Saurichthys would
have faced very little resistance as it swam through the water which
also suggests high swimming speed.
However
it is unlikely that Saurichthys was not a pursuit predator that chased
prey across open water, and this reasoning is based upon the size of
the pectoral fins. Pectoral fins are essentially hydroplanes that
counteract the downwards pitching effect of swimming by tail. Because
the tail is on the rear of the body it pushes rather than pulls the
body weight so that the main body ends up sinking without the support
of fins to keep it angled in the desired direction of travel. The
larger the pectoral fins, the more they can compensate and the faster
the fish can swim without unavoidably pitching down. This is why the
fastest swimming fish we know today have some of the proportionately
largest pectoral fins.
The
pectoral fins of Saurichthys however are tiny however and they would
have offered very little hydroplane support in swimming. This means
that while Saurichthys could combine the caudal and dorsal tail
positions with the streamlined body for high speed, it could not
maintain this speed over distance without pitching down for lack of
support from the pectoral fins. This means that Saurichthys could
only swim at speeds in short bursts, something that reveals that even
though Saurichthys could not chase prey across open water, it was
very well suited to the life of an ambush hunter.
Ambush
hunting requires the use of cover for the predator to hide in and here
the narrow body and small fins of Saurichthys would have been perfect
for lurking amongst water weeds and submerged debris as it could
operate in these locations without wedging its body or snagging and
tearing its fins. Also while no fossil evidence exists to support
this, it is reasonable to assume that in life Saurichthys would have
had a mottled or striped patterning to break up the shape of its body
to the eyes of prey as it lay in cover.
When
prey was identified Saurichthys probably would have slowly lined itself
for a strike while still in cover, constantly making fine adjustments
as it watched its prey moving and approaching closer. Once
Saurichthys gauged its target was within strike range it would
rapidly flick its tail and use the combined push of all of its rear
fins to shoot out of the undergrowth like an arrow towards its prey.
Once close enough, Saurichthys could open up its elongated jaws,
as much as third of the total length of the body, to seize its prey.
Saurichthys
was likely a predator of fish and quite possibly other vertebrates such
as amphibians. However an Italian specimen of a bolus (a collection
of animal parts that are indigestible for a specific predator so they
are regurgitated in pellet form) suggests that Saurichthys even
included small pterosaurs in its feeding, in this case often credited
as the genus Preondactylus. It is unknown if the Saurichthys in
question killed the pterosaur, or was merely scavenging the carcass
of a drowned individual, but it does offer a fascinating insight into
the aquatic ecosystems of the Triassic.
Further reading
- L'Infralias dans la Franche-Comt� [The Lower Lias of Franche-Comt�].
- M�moires de la Soci�t� d'�mulation du Doubs, 4e s�rie 10:287-486. -
M. J. Henry - 1876.
- Description d'une nouvelle esp�ce de Saurichthys
du gr�s a voltz de
Wasselonne. - Bulletin du Service de la carte G�ologique d'alsace et de
Lorraine 2:89-97. - F. Firtion - 1934.
- La faune ichthyologique de l'Eotrias du N. W. de Madagascar: le
neurocr�ne. - Cahiers de Pal�ontologie 1968:1-125. - L. Beltan - 1968.
- The Upper Triassic Fishes from Polzberg bei Lunz, Austria. -
Zoological Journal of the Linnean Society 60:1-93. - J. Griffith - 1977.
- Un nouveau Saurichthyidae (Pisces, Actinopterygii), Saurichthys
nepalensis n. sp. du Trias Inf�rieure des Annapurnas (Thakkhola, Nepal)
et sa significations pal�obiog�ographique. - Cybium 3e S�rie
2(4):17-28. - L. Beltan & P. Janvier - 1978.
- A new saurichthyid from the Upper Permian of Zhejiang, China. -
Vertebrata PalAsiatica 26(2):77-89. - X. Liu & F. Wei - 1988.
- Freshwater fish fauna from the Triassic of Northern Asia. - Mesozoic
Fishes 2—Systematics and Fossil Record 445-468. - E. K. Sytchevskaya -
1999.
- New species of Saurichthys (Actinopterygii:
Saurichthyidae) from
Middle Triassic (Anisian) of Yunnan Province, China. - Acta Geologica
Sinica 83(3):440-450. - F. Wu, Y. Sun, W. Hao, D. Jiang, G. Xu, Z. Sun
& A. Tintori - 2009.
- New Saurichthyid Actinopterygian Fishes from the Anisian (Middle
Triassic) of Southwestern China. - Acta Palaeontologica Polonica
56(3):581-614. - F. Wu, Y. Sun, G. Xu, W. Hao, D. Jiang & Z.
Sun - 2011.
- Remains of Saurichthys (Pisces, Actinopterygii)
from the Early
Triassic Wordie Creek Formation of East Greenland. - Bulletin of the
Geological Society of Denmark 93:93-100. - I. Kogan - 2011.
- Saurichthys and other fossil fishes from the late Smithian (Early
Triassic) of Bear Lake County (Idaho, USA), with a discussion of
saurichthyid palaeogeography and evolution. - Bulletin of Geosciences.
87: 543–570. - C. Romano, I. Kogan, J. Jenks, I. Jerjen & W.
Brinkmann - 2012.
- A new species of Saurichthys (Actinopterygii)
from the Middle
Triassic (early Ladinian) of the northern Grigna mountain (Lombardy,
Italy). - Rivista Italiana di Paleontologia e Stratigrafia 119:287-302
- A. Tintori - 2013.
- A new Saurichthys (Actinopterygii) from the
Spathian (Early Triassic)
of Chaohu (Anhui Province, China). - Rivista Italiana di Paleontologia
e Stratigrafia 120:157-164. - A. Tintori, J. D. Huang, D. Y. Jiang, Z.
Y. Sun, R. Motani & G. B. Chen - 2014.
- Redescription of Saurichthys madagascariensis
Piveteau, 1945
(Actinopterygii, Early Triassic), with implications for the early
saurichthyid morphotype. - Journal of Vertebrate Paleontology. 36 (4).
- Romano Kogan - 2016.
- Exceptional preservation reveals gastrointestinal anatomy and
evolution in early actinopterygian fishes. Scientific Reports 6:18758.
- Thodoris Argyriou, Marcus Clauss, Erin E. Maxwell, Heinz Furrer
& Marcelo R. S�nchez-Villagra - 2016.
- A new species of Saurichthys from the Middle
Triassic (Anisian) of
southwestern China. Vertebrata PalAsiatica 56:273-294. - F. X. Wu, Y.
L. Sun & G. Y. Fang - 2018.
- Internal cranial anatomy of Early Triassic species of Saurichthys
(Actinopterygii: Saurichthyiformes): implications for the phylogenetic
placement of †saurichthyiforms. - BMC Evolutionary Biology. 18 (1):
161. - Thodoris Argyriou, Sam Giles, Matt Friedman, Carlo Romano, Ilja
Kogan & Marcelo R. S�nchez-Villagra - 2018.
- Re-evaluation of the ontogeny and reproductive biology of the
Triassic fish Saurichthys (Actinopterygii,
Saurichthyidae)".
Palaeontology. 61: 559–574. - Erine E. Maxwell, Thodoris Argyriou,
Rudolf Stockar & Heinz Furrer - 2019.
- A new species of Saurichthys (Actinopterygii: Saurichtydae) from the
Middle Triassic of Monte San Giorgio. - Rivista Italiana di
Paleontologia e Stratigrafia. 127 (1): 49–71. - S. Renesto, F. Magnani
& R. Stockar - 2021.
Some big predatory fish
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