Conodonta

From Palaeos.org

Craniata
`--o Vertebrata
   |?- †Myllokunmingia fenjiaoa
   |?- †Haikouichthys ercaicunensis
   |--Conodonta
   `--+--Hyperoartia
      `--+--Anaspida
         `--+--Pteraspidomorphi 
            `==Thelodonti 
               |--+--Cephalaspidomorphi
               |  |--Galeaspida
               |  `--Pituriaspida
               `--o Gnathostomata
                  |--Placodermi
                  |--Chondrichthyes
                  `--o Teleostomi
                     |--Acanthodii
                     `--Osteichthyes
                        `--Tetrapoda
                           `--o Amniota
                              |--Sauropsida
                              `--Synapsida

These tiny teeth are quite common in Paleozoic rocks and sands (250 to 500 million years old), but body fossils were not found until the early 1980s. A well-preserved and unusually large genus, Promissum, was found in 1994. The teeth show complex specialized structures, and survived through the ages and the fossilization process due to their resilient phosphatic chemical composition; the teeth were probably used to filter out plankton and pass it down the throat.

Prior to the discovery of complete specimens, it wasn't entirely clear that these fossils were in fact teeth. For this reason, in the literature they are commonly referred to as conodont "elements", leaving the function unspecified. While it is still not certain whether these organs functioned as teeth for chewing or filter feeding apparatus, the localization of the elements in the head of the animal has led to the widespread use of the term "teeth".

Conodonts and their presumed relatives are known from the Cambrian to the Late Triassic. The earliest forms are identified as protoconodonts, followed by paraconodonts, followed by euconodonts (or "true conodonts"). In paraconodonts, the elements are simple conical structures that grew from around the base, while euconodonts have elements divisible into a basal and upper layer that grew by external accretion around the entire structure (Sweet & Donoghue 2001). These differences have been interpreted as indicating that paraconodonts had only the base of the element surrounded by secretory epithelium, whereas euconodont elements would have been retracted into pockets of epithelium and only exposed when the animal was feeding.

Following the discovery of eleven body fossils in Scotland and South Africa, most paleontologists think conodonts (which turn out to have fins with fin rays, chevron-shaped muscles, a notochord, and eyes) are in the phylum Chordata. Conodonts are today generally thought to be chordates/vertebrates but debate exists. Milsom and Rigby (2004) consider them to be vertebrates similar in appearance to modern hagfish and lampreys. Most paleontologists (following Szaniawski) place the protoconodonts in a phylum along with the chaetognath worms, indicating that they are not close relatives of the true conodonts. Complete fossils of conodont animals are rare, but the eleven imprints that have been found show an eel-like creature with 15 or, more rarely, 19 elements forming a bilaterally symmetrical array in the head, comprising a feeding apparatus radically different from the jaws of modern animals.

Cladistic analyses by Donoghue et. al (1998, 2000) suggest that conodonts are vertebrates. The paraconodonts (known only from teeth) are thought to be related, but the relationship is unclear. According to Donoghue, protoconodonts are not related to the rest.

Conodont teeth are phosphatic and their colour darkens when heated. They are therefore used as a proxy for thermal alteration in the host rock. This feature has made them a useful tool for petroleum exploration. The Conodont Alteration Index (CAI) is a scale which correlates conodont color to maximum rock temperature at depth.

Teeth are of three forms: coniform (cones), ramiform (bars), and pectiniform (platforms).

Phylogeny

See also Mikko Haaramo's conodont page.

<==Conodonta [Conodontophorida]
   |--Problematoconites Müller 1959 [Paraconodontida] DJ71
   |    `--*P. perforata Müller 1959 DJ71
   `--Euconodonta SD01
        |--Proconodontida SD01
        `--Conodonti SD01

Conodonta incertae sedis:

 Aspelundia fluegeli (Walliser 1964) WBN02
 Muellerodus cambricus Müller 1959 RNP03
 Westergaardodina DJ71
 Eoconodontus RNP03
 Prooneotodus gallatini Müller 1959 RNP03
 Protognathus praedelicatus Lane, Sandberg & Ziegler 1980 WM03
 Erika MG01
 Jumudontus gananda PBJ03
 Tripodus laevis PBJ03
 Paracordylodus gracilis PBJ03
 Bergstroemognathus extensus PBJ03
 Kallidontus nodosus PBJ03
 Polonodus corbatoi PBJ03
 Oelandodus elongatus PBJ03
 Stolodus stola PBJ03
 Stiptognathus borealis PBJ03
 Cornuodus longibasis PBJ03
 Diaphorodus PBJ03
 Fahraeusodus marathonensis PBJ03
 Juanognathus variabilis PBJ03
 Parapanderodus striatus PBJ03
 Stultodontus costatus PBJ03
 Eucharodus parallellus PBJ03
 Erismodus asymmetricus PBJ03
 Curtognathus PBJ03
 Neomultoistodus compressus PBJ03
 Pteracontiodus cryptodens PBJ03
 Paraprioniodus costatus PBJ03
 Streptognathodus bellus Chernyk & Ritter 1997 CL02
 Mockina slovakensis W03
 Filodontus Pyle, Barnes & Ji 2003 PBJ03
   `--*F. filosus (Ethington & Clark 1964) [=Scolopodus filosus] PBJ03
 Prosagittodontus RNP03
   |--P. eureka Müller 1959 RNP03
   `--P. minimus Müller & Hinz 1991 RNP03
 Leptochirognathus Branson & Mehl 1943 PBJ03
   |--L. quadratus PBJ03
   `--L. wilcoxi Pyle, Barnes & Ji 2003 PBJ03
 Oepikodus PBJ03
   |--O. communis PBJ03
   `--O. evae PBJ03
 Microzarkodina parva PBJ03
 Colaptoconus PBJ03
   |--C. multiplicatus PBJ03
   `--C. quadraplicatus PBJ03
 Walliserodus SS05
   |--W. curvatus (Branson & Branson 1947) WBN02 (see below for synonymy)
   |--W. declivis PBJ03
   `--W. ethingtoni PBJ03
 Furnishina RNP03
   |--F. alata Szaniawski 1971 RNP03
   `--F. polonica Szaniawski 1971 RNP03
 Acodus Pander 1856 DJ71
   |--*A. erectus Pander 1856 DJ71
   |--A. cambricus Nogami 1967 DJ71
   |--A. deltatus PBJ03
   |--A. kechikaensis PBJ03
   |--A. neodeltatus PBJ03
   `--A. oneotensis Furnish 1938 DJ71
 Histiodella PBJ03
   |--H. altifrons PBJ03
   |--H. holodentata PBJ03
   `--H. sinuosa PBJ03
 Paroistodus PBJ03
   |--P. originalis PBJ03
   |--P. parallelus PBJ03
   `--P. proteus PBJ03
 Tropodus PBJ03
   |--T. australis PBJ03
   |--T. comptus PBJ03
   `--T. sweeti PBJ03
 Protoprioniodus PBJ03
   |--P. aranda PBJ03
   |--P. nyinti PBJ03
   `--P. simplicissimus PBJ03
 Paltodus PBJ03
   |--P. jemtlandicus PBJ03
   `--P. subequalis PBJ03
 Epigondolella DV03
   |--E. abneptis DV03
   |    |--E. a. abneptis DV03
   |    `--E. a. spalatus DV03
   |--E. bidentata DV03
   |--E. carinata DV03
   |--E. postera DV03
   `--E. slovakensis DV03
 Ancyrodella KU04
 Bispathodus Müller 1962 BWZ02
   `--B. aculeatus E03
 *Bipennatus bipennatus (Bischoff & Ziegler 1957) D02
 Pelekysgnathus Klapper & Johnson 1980 V03
   `--P. planus Sannemann 1955 D02
 Pandorinellina KU04
   |--P. exigua (Philip 1966) V02
   |--P. expansa (Uyeno & Mason 1975) V02
   `--P. insita (Stauffer 1940) D02
 Klapperina D02
 Playfordia Glenister & Klapper 1966 [Playfordiidae] D02
   `--P. primitiva (Bischoff & Ziegler 1957) D02
 Eotaphrus D02
 Streptotaxis Uyeno & Klapper 1980 V03
   `--S. furnishi Klapper 1980 V03
 Plectospathodus alternatus TC71
 Trichonodella inconstans TC71
 Variabiloconus bassleri FEZ05
 Polygnathellus curvatus Ulrich & Bassler 1926 KU04
 Nothognathella sublaevis Sannemann 1955 KU04
 Paragondolella inclinata AFZ04
 Budurovignathus mungoensis AFZ04
 Phragmodus undatus SS05
 Belodina confluens SS05
 Archeognathus Cullison 1938 SS05
 Stereoconus Branson & Mehl 1933 SS05
   |--*S. gracilis Branson & Mehl 1933 [incl. S. robustus Branson & Mehl 1933] SS05
   `--S. plenus Branson & Mehl 1933 SS05
 Pseudooneotodus Drygant 1974 SS05
   `--*P. bechmanni (Bischoff & Sanneman 1958) [=Oneotodus beckmanni] SS05
 Apatognathus varians ZP86
 Neospathodus TE01
   |--N. bransoni CB86
   |--N. constricta TE01
   |--N. dieneri TE01
   |--N. homeri TE01
   |--N. hungaricus TE01
   |--N. pakistanensis TE01
   `--N. triangularis TE01
 Neogondolella TE01
   |--N. excelsa TE01
   |--N. mombergensis TE01
   |--N. navicula TE01
   `--N. serrata DX84
 Sagittodontus Rhodes 1953 DJ71
   |--*S. robustus Rhodes 1953 DJ71
   |--S. asymmetricus [=Furnishina asymmetrica] DJ71
   |--S. dahlmani Müller 1959 [incl. S. dunderbergiae Müller 1959] DJ71
   `--S. furnishi (Müller 1959) [=Furnishina furnishi] DJ71
 Gothodus costulatus DJ71
 Acontiodus latus DJ71
 Strachanognathus Rhodes 1953 DJ71
 Hindeodella qipanensis CB86
 Laterlonchodina simplex CB86
 Acodina cuspidata (Stauffer 1940) WSQ86
 Oneotodus DJ71

Walliserodus curvatus (Branson & Branson 1947) WBN02 [incl. Paltodus acustatus Branson & Branson 1947 SS05, Panderodus acostatus SS05]

* Type species of generic name indicated

References

[AFZ04] Amati, L., R. M. Feldmann & J.-P. Zonneveld. 2004. A new family of Triassic lobsters (Decapoda: Astacidea) from British Columbia and its phylogenetic context. Journal of Paleontology 78 (1): 150-168.

[BWZ02] Bardashev, I. A., K. Weddige & W. Ziegler. 2002. The phylomorphogenesis of some Early Devonian platform conodonts. Senckenbergiana Lethaea 82: 375-451.

[CL02] Caridroit, M., A. Lamerandt, J.-M. Dégardin, A. F. de Dios & D. Vachard. 2002. Discovery of radiolaria and conodonts in the Carboniferous – Permian of San Salvador (Puebla, Mexico); biostratigraphic implications. Comptes Rendus Palevol 1: 205-211.

[CB86] Chen D.-Q. & Bao H. 1986. Lower Permian ostracodes from the Chihsia Formation of Jurong and Longtan, Jiangsu Province. Acta Micropalaeontologica Sinica 3 (2): 107-132.

[DV03] Dalla Vecchia, F. M. 2003. New morphological observations on Triassic pterosaurs. In Evolution and Palaeobiology of Pterosaurs (E. Buffetaut & J.-M. Mazin, eds) Geological Society Special Publications 217: 23-44. The Geological Society: London.

[DX84] Ding Y., Xia G., Duan C., Li W., Liu X. & Liang Z. 1984. Study on the early Permian stratigraphy and fauna in Zhesi district, Nei Mongol Zizhiqu (Inner Mongolia). Bulletin Tianjin Institure Geol. Min. Res. 10.

[DJ71] Druce, E. C., & P. J. Jones. 1971. Cambro-Ordovician conodonts from the Burke River Structural Belt, Queensland. Commonwealth of Australia, Bureau of National Development, Bureau of Mineral Resources, Geology and Geophysics, Bulletin 110: 1-159.

[D02] Dzik, J. 2002. Emergence and collapse of the Frasnian conodont and ammonoid communities in the Holy Cross Mountains, Poland. Acta Palaeontologica Polonica 47: 565-650.

[E03] Edgell, H. S. 2003. Upper Devonian Charophyta of Western Australia. Micropaleontology 49 (4): 359-374.

[FEZ05] Feng, H., B.-D. Erdtmann & Y. Zhang. 2005. Taxonomy and phylogeny of Staurograptus Emmons from the base of the Ordovician. Palaeontology 48 (5): 1007-1019.

[KU04] Klapper, G., T. T. Uyeno, D. K. Armstrong & P. G. Telford. 2004. Conodonts of the Williams Island and Long Rapids Formations (Upper Devonian, Frasnian – Famennian) of the Onakawana B Drillhole, Moose River Basin, northern Ontario, with a revision of the Lower Famennian species. Journal of Paleontology 78: 371-387.

[MG01] Märss, T., & P.-Y. Gagnier. 2001. A new chondrichthyan from the Wenlock, Lower Silurian, of Baillie-Hamilton Island, the Canadian Arctic. Journal of Vertebrate Paleontology 21 (4): 693-701.

[PBJ03] Pyle, L. J., C. R. Barnes & Z. Ji. 2003. Conodont fauna and biostratigraphy of the Outram, Skoki, and Owen Creek Formations (Lower to Middle Ordovician), Wilcox Pass, Alberta, Canada. Journal of Paleontology 77 (5): 958-976.

[RNP03] Robson, S. P., G. S. Nowlan & B. R. Pratt. 2003. Middle to Upper Cambrian linguliformean brachiopods from the Deadwood Formation of subsurface Alberta and Saskatchewan, Canada. Journal of Paleontology 77 (2): 201-211.

[SS05] Sansom, I. J., & M. P. Smith. 2005. Late Ordovician vertebrates from the Bighorn Mountains of Wyoming, USA. Palaeontology 48 (1): 31-48.

[SD01] Sweet, W. C., & P. C. J. Donoghue. 2001. Conodonts: past, present, future. Journal of Paleontology 75 (6): 1174-1184.

[TC71] Thomson, K. S., & K. S. W. Campbell. 1971. The structure and relationships of the primitive Devonian lungfish – Dipnorhynchus sussmilchi (Etheridge). Yale University Peabody Museum of Natural History Bulletin 38: 1-109.

[TE01] Tong, J., & D. H. Erwin. 2001. Triassic gastropods of the southern Qinling Mountains, China. Smithsonian Contributions to Paleobiology 92: 1-47.

[V03] Valiukevičius, J. 2003. Devonian acanthodians from Severnaya Zemlya Archipelago (Russia). Geodiversitas 25: 131-204.

[WSQ86] Wang C.-Y., Shi C.-G. & Qu G.-S. 1986. Conodonts and ostracodes from the Devonian "Heitai Formation" of Mishan County, Heilongjiang Province. Acta Micropalaeontologica Sinica 3 (2): 205-214.

[WM03] Webster, G. D., C. G. Maples, R. Mawson & M. Dastanpour. 2003. A cladid-dominated Early Mississippian crinoid and conodont fauna from Kerman Province, Iran and revision of the glossocrinids and rhenocrinids. Journal of Paleontology 77 (Suppl 3): 1-35.

[W03] Wellnhofer, P. 2003. A Late Triassic pterosaur from the Northern Calcareous Alps (Tyrol, Austria). In Evolution and Palaeobiology of Pterosaurs (E. Buffetaut & J.-M. Mazin, eds) Geological Society Special Publications 217: 5-22. The Geological Society: London.

[WBN02] Won, M.-Z., R. B. Blodgett & V. Nestor. 2002. Llandoverian (Early Silurian) radiolarians from the Road River Formation of east-central Alaska and the new family Haplotaeniatumidae. Journal of Paleontology 76 (6): 941-964.

[ZP86] Zhang, R., & J. Pojeta, Jr. 1986. New bivalves from the Datang Stage, Lower Carboniferous, Guangdong Province, China. Journal of Paleontology 60 (3): 669-679.

Credits

Intro BILL 061113; phylogeny Christopher 13:13, 6 January 2011 (UTC)