Biology:Ptyctodus

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Short description: Extinct genus of fishes

Ptyctodus
Temporal range: late Devonian 383.7–360.7 Ma
Ptyctodus compressus.jpg
Ptyctodus
Scientific classification e
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Placodermi
Order: Ptyctodontida
Family: Ptyctodontidae
Genus: Ptyctodus
Pander, 1858
Species

Ptyctodus bradyi
Ptyctodus calceolus
Ptyctodus compressus
Ptyctodus ferox
Ptyctodus molaris
Ptyctodus panderi

Ptyctodus is an extinct armour-plated fish of the late Devonian.[1] Ptyctodus belongs to the family Ptyctodontidae and is of the class Placodermi. They share a close resemblance to modern day chimaeras (Holocephali). Fossils of this armour-plated fish have been found in locations such as in Russia, the Michigan Basis,[2] and Arizona, United States.[3]

Description and paleobiology

Ptyctodus species come in a variety of different sizes, measured data shows three specimens being 94 millimeters, 24 millimeters, 22 millimeters in length, 23 millimeters, 6 millimeters, 4 millimeter in height, and 18 millimeters, 7 millimeters, and 4 millimeters in thickness.[4] Through time, an evolutionary morphological trait is that the species within Ptyctodontidae reduce the dermal armour.[5] The dentition of the Ptyctodus has dental elements that are very similarly observed in chimaeroids.[6] Its dental plates are compressed into a thin cutting edge behind the symphysis and measure 3 inches in thickness and several inches in length.[6] The tritors are expressed as fine punctae in parallel rows.[4] Ptyctodus teeth are very close together in a way that they are like a fish tooth conglomerate.[7] They were also armed with dorsal fin spines closely seen in Hetercanthus and Phlyctaenacanthus.[6] Just like the other members of the family of Ptyctodontidae, there is a sexual dimorphism between the genders of Ptyctodus in the pelvic region where the characteristics are different; males had claspers, while females had large scale like pelvic fins along with their endoskeleton.[8]

Ptyctodus lived in a nektonic carnivore type-ecology and in carbonate, lagoonal, and shallow subtidal environments.[1] Due to structure and shape of the teeth Ptyctodus would easily be able to crush shellfish like organisms at the bottom of the ocean floors, feeding mainly off of that. They also must seem to have been very agile swimmers, able to escape predators, like arthrodires.[2][failed verification]

Species

Species of the Ptyctodus:

  • Ptyctodus bradyi was discovered by the basis of two tooth plates in 1942 by Hussakof on Mt. Elden in Arizona.[3]
  • Ptyctodus calceolus
  • Ptyctodus compressus first documentation was in 1870[4]
  • Ptyctodus ferox
  • Ptyctodus molaris
  • Ptyctodus panderi

Timeline

Timeline of Ptyctodus along with other species within the Ptyctodontidae family <timeline> ImageSize = width:1000px height:auto barincrement:15px PlotArea = left:10px bottom:50px top:10px right:10px

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from: -416    till: -411.2   color:earlydevonian    text:Loch.
from: -411.2    till: -407   color:earlydevonian    text:Prag.
from: -407    till: -397.5   color:earlydevonian    text:Ems.
from: -397.5    till: -391.8   color:middledevonian    text:Eif.
from: -391.8    till: -385.3   color:middledevonian    text:Givetian
from: -385.3    till: -374.5   color:latedevonian    text:Frasnian
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color:middledevonian	bar:NAM2	from:	-397.5	till:	-391.8	text:	Goniosteus
color:middledevonian	bar:NAM3	from:	-397.5	till:	-385.3	text:	Desmoporella
color:middledevonian	bar:NAM4	from:	-397.5	till:	-378.1	text:	Campbellodus
color:middledevonian	bar:NAM5	from:	-397.5	till:	-374.5	text:	Ctenurella
color:middledevonian	bar:NAM6	from:	-397.5	till:	-359.2	text:	Denisonodus
color:middledevonian	bar:NAM7	from:	-397.5	till:	-359.2	text:	Ptyctodopsis
color:latedevonian	bar:NAM8	from:	-385.3	till:	-381.7	text:	Chelyophorus
color:latedevonian	bar:NAM9	from:	-385.3	till:	-381.7	text:	Eczematolepis
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color:latedevonian	bar:NAM11	from:	-385.3	till:	-381.7	text:	Ptyctodus
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from: -374.5    till: -359.2   color:latedevonian    text:Famennian
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from: -416    till: -359.2   color:devonian    text:Devonian

</timeline>

Gallery

References

  1. 1.0 1.1 "Ptyctodus Pander 1858". Gateway to the Paleobiology Database. http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=34272. 
  2. 2.0 2.1 Holman, Alan (1995). Life of the Great Lakes Basin: Precambrian to Pleistocene. University of Michigan Press. p. 153. 
  3. 3.0 3.1 Johnson, Heidemarie; Elliot, David (November 1996). "A New Ptyctodont (Placodermi) from the Upper Devonian Martin Formation of Northern Arizona, and an Analysis of Ptyctodont Phylogeny". Journal of Paleontology 70 (6): 994–1003. doi:10.1017/S0022336000038695. 
  4. 4.0 4.1 4.2 Branson, E (1922). "The Devonian of Missouri". Missouri Bureau of Geology and Mines 17 (2): 127–128. 
  5. Trinajstic, Kate; Long, John (2009). A new genus and species of Ptyctodont (Placodermi) from the Late Devonian Gneudna Formation, Western Australia, and an analysis of Ptyctodont phylogeny. 146. pp. 743–760. 
  6. 6.0 6.1 6.2 Eastman, Charles. "DEVONIAN FISHES OF IOWA". Iowa Geological Survey: 133. 
  7. Calvin, Samuel; Leonard, A (1897). "Iowa Geological Survey". Annual Report 7: 75. 
  8. Miles, Roger (October 1967). "Observations on the ptyctodont fish, Rhamphodopsis Watson". Zoological Journal of the Linnean Society 47 (311): 99–120. doi:10.1111/j.1096-3642.1967.tb01398.x. 

Wikidata ☰ Q30593733 entry