Editing Conodont (section)

=== Lone elements ===
Conodont elements consist of mineralised teeth-like structures of varying morphology and complexity. The evolution of [[mineralized tissues]] has been puzzling for more than a century. It has been hypothesized that the first mechanism of chordate tissue mineralization began either in the oral skeleton of conodonts or the dermal skeleton of early [[agnathans]].

The element array constituted a feeding apparatus that is radically different from the jaws of modern animals. They are now termed "conodont elements" to avoid confusion. The three forms of teeth, i.e., coniform cones, ramiform bars, and pectiniform platforms, probably performed different functions.

For many years, conodonts were known only from enigmatic tooth-like microfossils (200 micrometers to 5 millimeters in length<ref>{{cite web|last1=MIRACLE|title=Conodonts|url=http://www.ucl.ac.uk/GeolSci/micropal/conodont.html|access-date=26 August 2014}}</ref>), which occur commonly, but not always, in isolation and were not associated with any other fossil. Until the early 1980s, conodont teeth had not been found in association with fossils of the host organism, in a [[lagerstätte|konservat lagerstätte]].<ref name="Briggs-1983">{{Cite journal | last1 = Briggs | first1 = D. E. G. | last2 = Clarkson | first2 = E. N. K. | last3 = Aldridge | first3 = R. J. | title = The conodont animal | doi = 10.1111/j.1502-3931.1983.tb01993.x | journal = Lethaia | volume = 16 | issue = 1| pages = 1–14 | year = 1983| bibcode = 1983Letha..16....1B }}</ref> This is because the conodont animal was soft-bodied, thus everything but the teeth was unsuited for preservation under normal circumstances.

These microfossils are made of [[hydroxylapatite]] (a phosphatic mineral).<ref>{{cite journal | doi = 10.1016/j.chemgeo.2006.03.004 | volume=233 | title=Chemical systematics of conodont apatite determined by laser ablation ICPMS | year=2006 | journal=Chemical Geology | pages=196–216 | last1 = Trotter | first1 = Julie A.| issue=3–4 | bibcode=2006ChGeo.233..196T }}</ref> The conodont elements can be extracted from rock using adequate solvents.<ref>{{cite journal | last1 = Jeppsson | first1 = Lennart | last2 = Anehus | first2 = Rikard | year = 1995| title = A Buffered Formic Acid Technique for Conodont Extraction | journal = Journal of Paleontology | volume = 69 | issue = 4| pages = 790–794 | jstor = 1306313 | doi = 10.1017/s0022336000035319 | bibcode = 1995JPal...69..790J | s2cid = 131850219 }}</ref><ref>{{cite book | doi = 10.1007/978-94-017-0581-3_27 | year=2001 | pages=318–330 | last1 = Green | first1 = Owen R.| title=A Manual of Practical Laboratory and Field Techniques in Palaeobiology | chapter=Extraction Techniques for Phosphatic Fossils | isbn=978-90-481-4013-8 }}</ref><ref>{{cite journal | doi = 10.1016/j.chemgeo.2016.03.023 | volume=431 | title=Effects of extraction protocols on the oxygen isotope composition of conodont elements | year=2016 | journal=Chemical Geology | pages=36–43 | last1 = Quinton | first1 = Page C.| bibcode=2016ChGeo.431...36Q }}</ref>

They are widely [[conodont biostratigraphy|used in biostratigraphy]]. Conodont elements are also used as [[paleothermometer]]s, a proxy for thermal alteration in the host rock, because under higher temperatures, the phosphate undergoes predictable and permanent color changes, measured with the [[conodont alteration index]]. This has made them useful for [[petroleum exploration]] where they are known, in rocks dating from the [[Cambrian]] to the Late [[Triassic]].