of
Gotland,
Sweden For a long time, the function and arrangement of conodont elements was enigmatic, since the whole animal was soft-bodied, with the sole exception of the mineralized elements. Upon the conodont animal's demise, the
soft tissues would decompose and the individual conodont elements would separate. However, in instances of exceptional preservation the conodont elements may be recovered in articulation. By closely observing these rare specimens, Briggs
et al. (1983)
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), 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
konservat lagerstätte. 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). The conodont elements can be extracted from rock using adequate solvents. They are widely
used in biostratigraphy. Conodont elements are also used as
paleothermometers, 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.
Full apparatus File:Hindeodus elements.jpg|Complete element set of the conodont
Hindeodus parvus File:Archeognathus primus.png|Preserved articulated association of conodont elements belonging to the species
Archeognathus primus (Ordovician, North America) The conodont apparatus may comprise a number of discrete elements, including the spathognathiform, ozarkodiniform, trichonodelliform, neoprioniodiform, and other forms. In the 1930s, the concept of conodont assemblages was described by Hermann Schmidt and by Harold W. Scott in 1934.
Element types '' – a conodont from the Upper Frasnian of Poland – photography taken in the Geological Museum of the Polish Geological Institute in Warsaw The arrangement of elements in
ozarkodinids and other complex conodonts was first reconstructed from extremely well-preserved
taxa by Briggs
et al. (1983), Conodont elements are organized into three different groups based upon shape. These groups of shapes are termed
S,
M, and
P elements. The
S and
M elements are ramiform, elongate, and comb-like structures. An individual element has a single row of many cusps running down the midline along its top side. These conodont elements are arranged towards the animal's anterior oral surface, forming an interlocking basket of cusps within the mouth. Cusp may point out towards the head of the animal, or back towards the tail. The number of
S and
M elements present as well as the direction they point may vary by
taxonomic group.
M (makellate) elements have a higher position in the mouth and commonly form a symmetrical shape akin to a horseshoe or pick.
S elements are further divided into three subtypes: •
S element - an unpaired
symmetrical ramiform structure at the front of the mouth. Sometimes known as an S0 element. •
S element - paired asymmetrical structures •
S element - paired highly asymmetrical, bipennate structures In
P elements, a pectiniform (comb-shaped) row of cusps transitions into a broad flat or ridged platform moving towards the base of the element. Platforms and cusps are only found along one side of the structure. Individual elements oriented vertically and arranged in pairs, with platforms and cusps pointing towards the animal's midline. They occur deeper in the throat than the S and M elements.
P elements are further divided into two subtypes: •
Pa element - blade-like structures •
Pb element - arched structures == The conodont animal ==