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A Tooth Whorl of Edestus heinrichi (Chondrichthyes, Eugeneodontiformes) Displaying Progressive Macrowear


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Edestus is a Middle Pennsylvanian chondrichthyan possessing symphyseal tooth whorls in both the upper and lower jaws. The curvature of the tooth whorls prevents most of the crowns of the opposing whorls from occluding with each other. For that reason, it has recently been hypothesized that the tooth whorls were used to slash prey with a vertical motion of the anterior part of the body, not to cut prey caught between them. A tooth of Edestus minor having a truncated, smoothly worn apex has been reported previously. Here, a partial tooth whorl of a different species, Edestus heinrichi, is described. The apices of the crowns are worn, so that the crown heights are reduced by about one third. The more labial (older) of the two preserved crowns shows more wear than the more lingual (younger) one. In contrast to the previously reported E. minor tooth, wear is observed to the serrations as well as to the apices of the crowns. The observed wear on both the E. minor tooth and on the E. heinrichi tooth whorl supports the recent hypothesis on the function of the tooth whorls. In both cases, the apices might have been abraded by attempted predation on or scavenging of large fish having skin covered with denticles or scales.
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A tooth whorl of Edestus heinrichi (Chondrichthyes,
Eugeneodontiformes) displaying progressive macrowear
Wayne M. Itano
Museum of Natural History, University of Colorado, Boulder, Colorado
Edestus is a Middle Pennsylvanian chondrichthyan possessing symphyseal tooth whorls
in both the upper and lower jaws. The curvature of the tooth whorls prevents most of the
crowns of the opposing whorls from occluding with each other. For that reason, it has
recently been hypothesized that the tooth whorls were used to slash prey with a vertical
motion of the anterior part of the body, not to cut prey caught between them. A tooth of
Edestus minor having a truncated, smoothly worn apex has been reported previously. Here,
a partial tooth whorl of a different species, Edestus heinrichi, is described. The apices of the
crowns are worn, so that the crown heights are reduced by about one third. The more labial
(older) of the two preserved crowns shows more wear than the more lingual (younger) one.
In contrast to the previously reported E. minor tooth, wear is observed to the serrations
as well as to the apices of the crowns. The observed wear on both the E. minor tooth and
on the E. heinrichi tooth whorl supports the recent hypothesis on the function of the tooth
whorls. In both cases, the apices might have been abraded by attempted predation on or
scavenging of large sh having skin covered with denticles or scales.
Keywords: Carboniferous, dental macrowear, Edestus, functional morphology
transactIons of the Kansas
acadeMy of scIence
Vol. 121, no. 1-2
p. 125-133 (2018)
Edestus Leidy, 1856, is a Middle Pennsylvanian
chondrichthyan genus having an unusual,
possibly unique, dental morphology. It
possessed symphyseal tooth whorls of
approximately equal dimensions in both the
upper and lower jaws, in contrast to the better-
known Helicoprion Karpinsky, 1899, which
possessed a large, symphyseal tooth whorl
only in the lower jaw (Bendix-Almgreen 1966;
Lebedev 2009; Tapanila et al. 2013). The
curvature of Edestus tooth whorls prevents
most of the crowns of the opposing whorls from
occluding with each other. If the tooth whorls
were used to cut prey trapped between them, by
closing the jaws, the more labial (anterior) teeth
would be nonfunctional, and it is not obvious
why they would be retained. An alternative
hypothesis, that the tooth whorls were used to
slash prey with a vertical motion of the anterior
part of the body has been proposed recently
(Itano 2014). The tooth whorls would have
extended outside the oral cavity, as in Figure
1. It should be noted that the tooth whorls in
Figure 1 are based on those of Edestus newtoni,
which has tooth whorls that are more curved
than other species of Edestus. How much of
the tooth whorls were supported by cartilage
and how much simply covered by skin is
not known. Edestus might have possessed a
exible quadrato-mandibular joint, as suggested
by Zangerl and Jeremiah (2004), to enable
sideways motion of the tooth whorls and to
allow it to close its mouth. However, fossil
evidence for such anatomical details is lacking.
There being no obvious biological analogs,
the paired tooth whorls of Edestus have
been compared to man-made tools such as
scissors or tweezers (Peyer 1968, p. 73). A
different human-tool analog, the leiomano, was
proposed by Itano (2014). The leiomano is an
indigenous Hawaiian weapon, consisting of a
club lined with shark teeth (Buck 1957). The
reproduction of a leiomano shown in Figure
2 is based on one observed on Cook’s third
voyage (Cook and King 1784, pl. 67, g. 1).
126 Itano
The reproduction is lined with teeth of the
tiger shark, Galeocerdo cuvier. Presumably,
the leiomano was swung by hand in an arc so
that the shark teeth would penetrate the skin
and then slice through the esh of a human
opponent. According to the hypothesis of Itano
(2014), Edestus tooth whorls were used in a
similar manner to kill or disable large prey.
An isolated tooth of Edestus minor with a
truncated, smoothly worn apex was reported
recently (Itano 2015a). The wear was
hypothesized to be caused by contact with the
skin of large prey having skin covered with
hard denticles or scales. The large amount of
wear implies that penetration of the skin was
difcult and might have required repeated
strikes. Microwear, consisting of scratches
oriented mainly transverse to the basal-apical
axis, has been observed on other teeth of
Edestus minor (Itano 2015b).
Recently, a partial tooth whorl of a different
species, Edestus heinrichi, was found, which
shows macrowear to the two most preserved
teeth (Figure 3). Such wear does not appear to
have been observed previously on teeth of E.
Institutional abbreviations: AMNH,
American Museum of Natural History, New
York, New York; ISM, Illinois State Museum,
Springeld, Illinois; NHMUK, Natural History
Museum, London, UK; TMM, Vertebrate
Paleontology Laboratory (formerly with the
Texas Memorial Museum), University of
Texas, Austin, Texas; UI, University of Illinois,
Urbana-Champaign, Illinois.
Systematic Paleontology:
Chondrichthyes Huxley, 1880
Euchondrocephali Lund and Grogan, 1997
Eugeneodontiformes Zangerl, 1981
Edestidae Jaekel, 1899
Edestus Leidy, 1856
Type species: Edestus vorax Leidy, 1856
Edestus heinrichi Newberry and Worthen, 1870
(Figures 3-5)
Holotype: UI X-442, a tooth whorl (Newberry
and Worthen 1870, pl. 1, g. 1). The holotype
is currently missing (D. Blake, personal
Figure 1. Hypothetical reconstruction of Edestus.
Tooth whorls are modeled on those of Edestus
newtoni. Other details of body are conjectural.
Drawing by Gary Raham,,
used with permission. Figure 2. Reproduction of a leiomano, an
indigenous Hawaiian weapon lined with shark
Transactions of the Kansas Academy of Science 121(1-2), 2018 127
communication, May 2013). Several casts are
extant, including AMNH FF 488, ISM 407040,
and NHMUK P.3151.
Material: AMNH FF 21226, a partial tooth
whorl, including two crowns, a small part of a
third crown, and parts of the bases.
Locality and age: Coal mine near Coulterville,
Randolph County, Illinois, USA. Shale bed
overlying the Herrin (No. 6) Coal, Pennsylvanian
Period, late Desmoinesian North American
Regional Stage (= late Moscovian Global Stage).
More precise geographic locality information is
on le at the AMNH.
Figure 3. Partial tooth whorl of Edestus heinrichi, AMNH FF 21226. A. Lateral view of whole
specimen. Labial end to left. Scale bar = 2 cm. B. Lateral view of most labial crown. Labial end to left.
Scale bar = 1 cm. Abbreviations: wa, worn apex; ws, worn serration; us, unworn serration.
128 Itano
Recent chronostratigraphic work, based on
conodont biostratigraphy and on interregional
correlation by use of major glacial-eustatic
cyclothems, allows rather precise dating of
the Herrin Coal (Falcon-Lang et al. 2011;
Falcon-Lang et al. 2018; Heckel 2008; Heckel
et al. 2005; Heckel et al. 2007). The Herrin
Coal lies within the Pawnee major cyclothem,
which is close to and below the Moscovian –
Kasimovian boundary. The Altamont and Lost
Branch major cyclothems lie above the Pawnee
major cyclothem and below the Desmoinesian
– Missourian boundary. The youngest known
Edestus remains are from the Altamont major
cyclothem in both North America (Lake Neosho
Shale Member of the Altamont Limestone)
(Hamm and Cicimurri 2005) and in Russia
(early Krevyakinian regional substage) (Lebedev
2001). The Altamont major cyclothem is the next
one above the Pawnee major cyclothem. Major
cyclothems are spaced by approximately 400 kyr.
AMNH FF 21226 is a partial tooth whorl.
Whether it represents part of an upper or lower
tooth whorl is not known. It contains the two
most labial crowns and parts of their bases (Fig.
3A). The apices are truncated, and the apical
surfaces are smooth and convex (Figs. 3A-B,
4A-B). The serrations on both the labial and
lingual edges of the crowns show wear (Figs.
3A-B, 5). The degree of wear to the serrations
is greater near the apices than near the bases
(Figs. 3A-B). The apex of the most labial crown
shows more wear than that of the second most
labial crown. Figure 6 shows an image of the
most labial crown rotated 12º counterclockwise
and overlaid on top of an image of the second
most labial crown. The outlined area represents
the amount of increased abrasion of the most
labial crown compared to that of the second
most labial crown.
Figure 4. AMNH FF 21226. A. Apical view of most labial crown. Labial end to left. Scale bar = 5
mm. B. Apical view of second most labial crown. Labial end to left. Scale bar = 5 mm.
Transactions of the Kansas Academy of Science 1211(1-2), 2018 129
Analogies of Edestus tooth whorls with
toothed rostra of sawsh and other
chondrichthyans: Functional analogies of
the tooth whorls of Edestus with the toothed
rostrum of the extant chondrichthyan, Pristis
(commonly called the sawsh), were proposed
soon after the discovery of Edestus (Hitchcock
1856; Leidy 1857) and have continued up to
the present (Long 2011, p. 107). On examining
a tooth whorl of Edestus, Louis Agassiz was of
the opinion that it had projected from the front
of the head of a sh, with the teeth pointing
outward and to the side and with another such
tooth whorl placed symmetrically on the other
side of the head (Hitchcock 1856). Placed
in this way, the pair of tooth whorls would
bear some resemblance to a Pristis rostrum,
which has teeth pointing outward on each side.
Agassiz’s reconstruction of Edestus differs in
two respects from more recent reconstructions.
First, the teeth are oriented in a horizontal,
rather than vertical, plane. Second, the apices
of the crowns of the opposite tooth whorls are
directed away from each other, rather than
toward each other.
The toothed rostrum of Pristis microdon is
known to be used both to sense prey and to
capture prey (by stunning or impaling prey,
or by pinning and manipulating them on the
substrate) (Wueringer et al. 2012). Of course,
only the latter function (capturing prey) is
thought to be analogous to Edestus. In the
absence of direct observational data, studies
of microwear of rostral teeth of the extant
sawshark Pristiophorus cirratus suggest that
it also uses its rostrum to capture prey, though
not necessarily to impale them (Nevatte et
al. 2017). Among both extant and extinct
chondrichthyans possessing sawsh-like rostra,
Schizorhiza, from the Upper Cretaceous, is
the one most closely analogous to Edestus.
Pristidae, Pristiophoridae, and Sclerorhyncidae
(other than Schizorhiza) have elongated,
narrow teeth arranged along the lateral margins
of the rostrum, forming comb-like structures.
In contrast, the rostral teeth of Schizorhiza
stroemeri are densely-packed, triangular, and
attened and have sharp cutting edges, so as
to form a double-edged, continuous, serrated,
cutting blade that could have been used as
a slashing weapon (Kirkland and Aguillón-
Martinez 2002; Smith et al. 2015).
The Aetobatus dentition: another example of
post-occlusal retention of teeth: The dentition
of the extant batoid Aetobatus provides an
example of a chondrichthyan in which teeth
are retained after the time when they occlude
Figure 5. AMNH FF 21226. Lateral view of part
of most labial crown, showing abraded apex
and abraded serrations. Labial end to right.
Scale bar = 5 mm. Abbreviations: ws, worn
serration; wa, worn apex.
Figure 6. AMNH FF 21226. Image of most
labial crown overlaid on top of that of the second
most labial crown. Outlined area represents the
amount of increased abrasion of the most labial
crown relative to that of the second most labial
crown. Labial end to right. Scale bar = 1 cm.
130 Itano
with the teeth of the opposite jaw, similarly
to Edestus. While its diet varies regionally,
Aetobatus narinari appears to be a hard-prey
specialist, feeding mainly on shelled gastropods
and bivalves and on hermit crabs (Schluessel,
Bennett and Collin 2010). A preserved jaw of
the white-spotted eagle ray, Aetobatus narinari,
was examined for this study (Fig. 7). Wear on
both the upper dentition (darker region in Fig.
7B) and the lower dentition (depressed region in
Fig. 7C) is clearly visible on this specimen. The
longitudinal (postero-anterior) extents of the
worn parts of the dentitions are 23 mm (upper)
and 55 mm (lower). This implies that about
3.2 cm (about 5 teeth) of the anterior part of
the lower dentition are retained after the point
where they occlude with the upper dentition.
Thus, the lower dentition projected signicantly
beyond the upper dentition. These observations
are consistent with those of Gudger (1914). At
least since Owen (1840-1845, p. 47), it has been
surmised that the projecting lower dentition
was used like a shovel, to dig prey from the
sandy sea oor. Direct observational evidence
for this behavior appears to be lacking. If the
post-occlusal lower dentition is used in this
way, such use does not seem to cause visibly
increased wear to the anteriormost part of the
dentition (Fig. 7C).
Macrowear on AMNH FF 21226, antemortem
or postmortem?: The wear observed on
the crowns of AMNH FF 21226 certainly
occurred prior to the death of the individual that
possessed them. If the wear had been due to
some postmortem process, such as tumbling in
sediment, one would expect to see wear also to
the lateral faces of the crowns and to the bases. In
an Edestus tooth whorl, teeth are shed at the labial
end and added at the lingual end, so the more
labial teeth are older. The fact that the more labial
tooth shows a greater degree of wear than the
other one implies that the tooth wear took place
over an extended period of time. The difference
in wear observed between the two crowns (Fig.
6) probably represents the amount of wear that
occurred during one tooth replacement interval.
Why is Edestus heinrichi macrowear
so rare?: The fact that wear is denitely
observed on AMNH FF 21226 and yet is so
rarely observed on other specimens of Edestus
heinrichi is puzzling. The author has directly
observed many crowns of E. heinrichi and
has not observed any other case in which
macrowear was apparent. Zangerl and Jeremiah
(2004, p. 10), in discussing a collection of many
E. heinrichi tooth whorls and isolated teeth,
stated that “True wear on any of the blades of
the Jeremiah collection has not been observed.”
The wear observed on AMNH FF 21226 is
unusual and must reect atypical circumstances.
The lack of wear on most crowns of Edestus
heinrichi may reect a normal diet of small or
soft prey that would not cause much damage to
the apices or serrations of the crowns, such as
small sh or soft-bodied cephalopods. A diet of
soft-bodied cephalopods has been hypothesized
for Helicoprion (Lebedev 2009; Ramsay et
al. 2015; Tapanila et al. 2013). Zangerl and
Jeremiah (2004, p. 17) suggested that Edestus
fed on jellysh.
Figure 7. Preserved jaws of white-spotted eagle
ray, Aetobatus narinari, from the Phillipines. W.
Itano personal collection, specimen number
2020. A. Both jaws. Upper dentition above,
lower dentition below. B. Occlusal view of
upper dentition. C. Oblique lateral view of lower
dentition. All scale bars = 2 cm.
Transactions of the Kansas Academy of Science 121(1-2), 2018 131
The observed wear both to the apices and
to the serrations of AMNH FF 21226 (Figs.
3A-B) gives some indication of the nature of
the surface that caused the abrasion. Abrasion
of the apices of both crowns could have been
caused by contact with a large, rigid, abrasive
surface. However, such a surface would not
have been able to contact the serrations along
the edges of the crowns. The wear observed
to the serrations could have resulted from
feeding-related attempts to cut through large
prey having an abrasive skin covered with
hard scales or denticles. In such a case, the
skin could have exed under pressure from the
crowns, so that there could have been contact
between the serrations and the skin.
The pronounced macrowear to the apices of
AMNH FF 21226 might have resulted from
repeated strikes to the skin of massive dead
or sessile prey. Live and mobile prey would
not likely have stayed stationary long enough
for such activity to have sawed through their
skin. Two possible scenarios come to mind:
1) The usual prey was depleted, leaving the
individual to feed on something other than its
ordinary diet. 2) The individual was injured
so that it was unable to feed on mobile prey
and was forced to feed on prey, dead or alive,
that was immobile or poorly mobile. The wear
observed on a tooth of Edestus minor (Itano
2015a) might have resulted from a similar set
of circumstances.
Possible multiple functions of the Edestus
dentition: The sharply-pointed and serrated
nature of the crowns of Edestus teeth suggests
a primary function of slicing through esh of
prey. Since the curvature of the tooth whorls
prevents all but the innermost two or three
crowns from occluding with those of the
opposing tooth whorl, this seems to imply a
vertical, whole-head (leiomano) motion to
utilize most of the teeth in slicing esh. This
does not preclude other, secondary functions
for the teeth. The innermost teeth could
have been used to grasp or cut prey caught
between them. Secondary functions of the
outer teeth are possible, but less likely, since
they do not seem to be optimally-adapted
to such functions. The extended Aetobatus
lower dentition can plausibly be used as a
shovel for digging up prey; the Edestus tooth
whorl, probably not. The horizontally attened
rostrum of Pristis appears better-adapted to
pinning and manipulating small prey against
the substrate than the Edestus tooth whorls.
The outer teeth of Edestus could have been
used to snag prey like jellysh (Zangerl and
Jeremiah 2004), but spike-like teeth would
probably function better for that purpose.
The macrowear observed to the apices and
serrations of the two preserved crowns on
AMNH FF 21226 appears to be antemortem
and to be a result of repeated contact with
relatively massive prey having an abrasive outer
covering. The fact that the worn surfaces of the
apices are roughly perpendicular to the basal-
apical axes of the crowns suggests that the teeth
were used to cut prey with a motion transverse
to the basal-apical axes, consistent with the
recent leiomano hypothesis of Itano (2014).
I thank C. Bollman for nding the tooth
whorl AMNH FF 21226. I thank D. Blake
(UI) and C. Widga (ISM) for information on
the whereabouts of the holotype of Edestus
heinrichi. I thank H. Blom (University of
Uppsala) for suggesting that Edestus teeth
be examined for wear that might indicate
the method of use of the tooth whorls and O.
Lebedev (Paleontological Institute, Moscow)
for discussions on reasons for the scarcity of
Edestus teeth displaying wear. I thank two
anonymous reviewers for raising issues that
lead to improvements in the manuscript.
132 Itano
lIterature cIted
Bendix-Almgreen, S.E. 1966. New
investigations of Helicoprion from the
Phosphoria Formation of south-east Idaho,
U.S.A. Biologiske Skrifter udgivet af det
Kongelige Danske Videnskabernes Selskab
Buck, P.H., 1957. War and weapons. pp. 417-
585 in Buck, P.H. (ed.), Arts and crafts
of Hawaii. B. P. Bishop Museum Special
Publication 45. Bishop Museum Press,
Honolulu, Hawaii.
Cook, J. and King, J. 1784. A voyage to the
Pacic Ocean, 3. Stockdale, Scatcherd &
Whitaker, Fielding, Hardy, London.
Falcon-Lang, H., Heckel, P.H., DiMichele,
W.A., Blake, B.M., Jr., Easterday, C.R., Eble,
C.F., Elrick, S., Gastaldo, R.A., Greb, S.F.,
Martino, R.L., Nelson, W.J., Pfefferkorn,
H.W., Phillips, T.L. and Rosscoe, S.J.
2011. No major stratigraphic gap exists
near the Middle-Upper Pennsylvanian
(Desmoinesian-Missourian) boundary in
North America. Palaios 26:125-139.
Falcon-Lang, H., Nelson, W.J., Heckel,
P.H. and DiMichele, W.A. 2018. New
insights on the stepwise collapse of the
Carboniferous Coal Forests: Evidence
from cyclothems and coniferopsid tree-
stumps near the Desmoinesian-Missourian
boundary in Peoria County, Illinois, USA.
Palaeogeography, Palaeoclimatology,
Palaeoecology 490:375-392.
Gudger, E.W. 1914. History of the spotted
eagle ray, Aëtobatus narinari, together with
a study of its external structures. Carnegie
Institution of Washington 183:241-323.
Hamm, S.A. and Cicimurri, D.J. 2005.
Middle Pennsylvanian (Desmoinesian)
chondrichthyans from the Lake Neosho
Shale Member of the Altamont Limestone
in Montgomery County, Kansas. Paludicola
Heckel, P.H. 2008. Pennsylvanian cyclothems
in Midcontinent North America as far-eld
effects of waxing and waning of Gondwana
ice sheets. pp. 275-289 in Fielding, C.R.,
Frank, T.D., Isbell, J.L. (eds.), Resolving the
Late Paleozoic Ice Age in Time and Space:
Geological Society of America Special
Paper 441. Geological Society of America,
Boulder, Colorado.
Heckel, P.H., Alekseev, A.S., Barrick, J.E.,
Boardman, D.R., Chernykh, V.V., Davydov,
V.I., Forke, H.C., Goreva, N.V., Luppold,
F.W., Mendez, C.A., Nemyrovska, T.I.,
Ueno, K., Villa, E. and Work, D.M. 2005.
Cyclothem [sequence-stratigraphic] correlation
and biostratigraphy across the Moscovian-
Kasimovian and Kasimovian-Gzhelian Stage
boundaries (Upper Pennsylvanian Series) in
North America and Eurasia. Newsletter on
Carboniferous Stratigraphy 23:36-44.
Heckel, P.H., Alekseev, A.S., Barrick,
J.E., Boardman, D.R., Goreva, N.V.,
Nemyrovska, T.I., Ueno, K., Villa, E. and
Work, D.M. 2007. Cyclothem [“digital”]
correlation and biostratigraphy across the
global Moscovian-Kasimovian-Gzhelian
stage boundary interval (Middle-Upper
Pennsylvanian) in North America and
eastern Europe. Geology 35(7):607-610.
Hitchcock, E. 1856. Account of the discovery
of the fossil jaw of an extinct family
of sharks, from the Coal Formation.
Proceedings of the American Association
for the Advancement of Science 9:229-230.
Huxley, T.H. 1880. On the application of the
laws of evolution to the arrangement of the
Vertebrata, and more particularly of the
Mammalia. Proceedings of the Scientic
Meetings of the Zoological Society of
London 1880:649-662.
Itano, W.M. 2014. Edestus, the strangest
shark? First report from New Mexico,
North American paleobiogeography, and a
new hypothesis on its method of predation.
Mountain Geologist 51(3):201-221.
Itano, W.M. 2015a. An abraded tooth
of Edestus (Chondrichthyes,
Eugeneodontiformes): evidence for a unique
mode of predation. Transactions of the
Kansas Academy of Science 118(1-2):1-9.
Transactions of the Kansas Academy of Science 121(1-2), 2018 133
Itano, W.M. 2015b. Microwear observed
on teeth of Edestus minor: evidence for
an unusual feeding strategy. Journal of
Vertebrate Paleontology Program and
Jaekel, O. 1899. Ueber die Organisation der
Petalodonten. Zeitschrift der Deutschen
Geologischen Gesellschaft 51(2):258-298.
Karpinsky, A.P. 1899. Über die Reste
von Edestiden und die neue Gattung
Helicoprion. Verhandlungen der Russisch-
Kaiserlichen Mineralogischen Gesellschaft
Kirkland, J.I. and Aguillón-Martinez, M.C.
2002. Schizorhiza: a unique sawsh
paradigm from the Difunta Group, Coahuila,
Mexico. Revista Mexicana de Ciencias
Geológicas 19(1):16-24.
Lebedev, O.A. 2001. Chapter 7. Pozvonochnye
[Vertebrates]. pp. 92-104 in Makhlina, M.K.
et al. (eds.), Srednij karbon Moskovskoy
sineklizy (yuzhnaya chast’). Tom 2 [Middle
Carboniferous of southern Moscow
Syneclise (southern part). Vol. 2]. Nauchnyi
Mir, Moscow.
Lebedev, O.A. 2009. A new specimen
of Helicoprion Karpinsky, 1899 from
Kazakhstanian Cisurals and a new
reconstruction of its tooth whorl position
and function. Acta Zoologica (Stockholm)
90(Suppl. 1):171-182.
Leidy, J. 1856. Indications of ve species,
with two new genera, of extinct shes.
Proceedings of the Academy of Natural
Sciences of Philadelphia 7:414.
Leidy, J. 1857. Remarks on certain extinct
species of shes. Proceedings of the
Academy of Natural Sciences of
Philadelphia 8:301-302.
Long, J.A. 2011. The Rise of Fishes, 2nd
Edition. Johns Hopkins University Press,
Baltimore, MD, 287 pp.
Lund, R. and Grogan, E.D. 1997. Relationships
of the Chimaeriformes and the basal
radiation of the Chondrichthyes. Reviews in
Fish Biology and Fisheries 7(1):65-123.
Nevatte, R.J., Wueringer, B.E., Jacob, D.E.,
Park, J.M. and Williamson, J.E. 2017. First
insights into the function of the sawshark
rostrum through examination of rostral
tooth microwear. Jounal of Fish Biology
Newberry, J.S. and Worthen, A.H. 1870.
Descriptions of vertebrates. Geological
Survey of Illinois 4:343-374.
Owen, R. 1840-1845. Odontography, Vol. 1.
Hippolyte Bailliere, London, 168 pp.
Peyer, B. 1968. Comparative Odontology.
University of Chicago Press, Chicago, 347 pp.
Ramsay, J.B., Wilga, C.D., Tapanila, L., Pruitt,
J., Pradel, A., Schlader, R. and Didier,
D.A. 2015. Eating with a saw for a jaw:
functional morphology of the jaws and
tooth-whorl in Helicoprion davisii. Journal
of Morphology 276(1):47-64.
Schluessel, V., Bennett, M.B. and Collin, S.P.
2010. Diet and reproduction in the white-
spotted eagle ray Aetobatus narinari from
Queensland, Australia and the Penghu
Islands, Taiwan. Marine and Freshwater
Research 61(11):1278-1289.
Smith, M.M., Riley, A., Fraser, G.J.,
Underwood, C., Welton, M., Kriwet, J.,
Pfaff, C. and Johanson, Z. 2015. Early
development of rostrum saw-teeth in a fossil
ray tests classical theories of the evolution
of vertebrate dentitions. Proceedings of the
Royal Society B 282(1816):20151628.
Tapanila, L., Pruitt, J., Pradel, A., Wilga, C.D.,
Ramsay, J.B., Schlader, R. and Didier,
D.A. 2013. Jaws for a spiral-tooth whorl:
CT images reveal novel adaptation and
phylogeny in fossil Helicoprion. Biology
Letters 9(2):20130057.
Wueringer, B.E., Squire, L., Jr., Kajiura,
S.M., Hart, N.S. and Collin, S.P. 2012.
The function of the sawsh’s saw. Current
Biology 22(5):R150-R151.
Zangerl, R. 1981. Chondrichthyes I: Paleozoic
elasmobranchii. pp. 1-115 in Schultze, H.-P.
(ed.), Handbook of Paleoichthyology 3A.
Gustav Fischer Verlag, Stuttgart, Germany.
Zangerl, R. and Jeremiah, C. 2004. Notes on
the tooth “saw blades” of Edestus, a late
Paleozoic chondrichthyan. Mosasaur 7:9-18.
... Furthermore, extrapolating the anatomy and joints of the E. heinrichi jaw to the other three species is regarded here as reasonable, with some consideration. The asymmetric species E. triserratus and E. minor have whorls that exhibit a greater degree of curvature, leading Itano [8,38,39,40] to imagine the whorls to curl outside the mouth for a vertical slashing motion. The evidence used for this hypothesis include several specimens of Edestus teeth showing wear patterns that are predominantly transverse to the crown (i.e., parallel to the base) [38,39,40]. ...
... The asymmetric species E. triserratus and E. minor have whorls that exhibit a greater degree of curvature, leading Itano [8,38,39,40] to imagine the whorls to curl outside the mouth for a vertical slashing motion. The evidence used for this hypothesis include several specimens of Edestus teeth showing wear patterns that are predominantly transverse to the crown (i.e., parallel to the base) [38,39,40]. This wear pattern is entirely consistent with the anatomy and functional reconstruction of FMNH PF 2204 [2], showing that Edestus whorls were positioned in opposition inside the mouth, and that the biting motion involved anterior-posterior slicing with the lower whorl. ...
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This study reevaluates the tooth morphology used to define species within the genus Edestus (Chondrichthyes, Euchondrocephali). Known as the scissor tooth shark, Edestus produced a unique dentition of spiraled tooth families positioned in the symphysis (midline) of the upper and lower jaws. Morphometric analysis of more than 200 ejected teeth and intact spiral tooth whorls demonstrates that teeth from the upper and lower whorls differ in shape and ontogeny. Comparison of these data to the type specimens of 13 existing species reduces the number of morphologically distinct Edestus to just four species and refines the stratigraphic occurrence and expansion of the group. E. triserratus has a narrow bullet-shaped crown that points anteriorly and has roots of intermediate length. E. minor crowns have a wider triangular base, whereas the crowns of E. heinrichi form nearly equilateral triangles and are supported by an elongated root. E. vorax, which also has roughly equilateral triangular crowns, has short and deep roots, and is only known from very large specimens that are distinct from the growth series of E. heinrichi. Tooth and whorl morphologies among the species are consistent with cranial anatomy observed in a juvenile E. heinrichi and with transverse tooth-wear patterns to suggest Edestus used a forward to backward slicing motion to bite its prey. Extrapolating body size from tooth whorl length provides a conservative estimate that E. heinrichi could exceed 6.7 m in length. Edestus fossils are recovered from coastal marine to estuarine deposits spanning roughly six million years (313-307 Ma). Edestus first appears in England during the latest Bashkirian (313 Ma, Carboniferous), a few million years after its most closely resembling genus Lestrodus. Diversification and range expansion of Edestus coincides with the Moscovian transgression that flooded Laurentia and the Russian platform.
... The fact that the abraded surface is roughly perpendicular to the basal-apical axis of the crown appears to support the slashing-mode hypothesis over the scissors-mode hypothesis. Similar apical wear has recently been reported on two crowns of a partial tooth whorl of E. heinrichi from a shale bed overlying the Herrin (No. 6) Coal (Pennsylvanian, late Desmoinesian = late Moscovian) of Randolph County, Illinois, USA (Itano, 2018). ...
... The extant batoid Aetobatus narinari is an example of a chondrichthyan in which teeth are retained beyond the point at which they occlude with the teeth of the other jaw. Photographs of the upper and lower dentitions of a single individual were published previously (Itano, 2018, fig. 7A-C). ...
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The symphyseal tooth whorls of the Carboniferous chondrichthyan Edestus consist of files of teeth having sharply-pointed, serrated crowns, joined at their bases. A single tooth whorl was present in each jaw. How these tooth whorls functioned is unclear, since their convex curvature allows only a few of the most lingual crowns of opposing tooth whorls to occlude. Rather than working in opposition, like scissors, the more labial teeth might have been used to cut and disable prey with a vertical motion of the anterior part of the body. Provided the scratches observed on the surface of Edestus teeth can be inferred to have been generated in the process of feeding, their orientation might be used to distinguish whether the teeth were used mainly in occlusion, to cut prey trapped between the jaws, or mainly to cut prey situated outside the oral cavity. Edestus minor teeth having unusually good surface preservation were examined for microwear. The teeth are from the Strawn Group (Desmoinesian, Middle Pennsylvanian) of San Saba County, Texas, USA. The best-preserved crown surfaces display scratches 50 to 500 micrometers long. The scratches are oriented predominantly transversely to the basal-apical axis. This observation appears to support the vertical slashing hypothesis. However, the possibility that interaction with the substrate contributed to the observed wear cannot be discounted.
... Dozens of blades and hundreds of ejected Edestus teeth have been collected from Pennsylvanian age (330 million years ago) marine shale deposits of midwestern United States and Britain, but cranial material is exceedingly rare. In the absence of anatomical context, functional models of Edestus propose comparisons to slashing sawfish rostrums (Eastman, 1902;Hay, 1909), shearing scissor jaws (Peyer, 1968;Zangerl and Jeremiah, 2004), or fixed vertical slashing weapons (Itano, 2014(Itano, , 2015(Itano, , 2018. Hay (1912) described a specimen of Edestus mirus having blades positioned at the jaw symphysis, though only cartilages at the anteriormost site of attachment were preserved. ...
... (1) loose attachment of the blades to the jaw and shearing passage of opposing blades (scissor: Zangerl and Jeremiah, 2004); (2) large rotations of fixed jaw joints (vertical slashing: Itano, 2014Itano, , 2015Itano, , 2018; or (3) greatly protruding blades (sawfish : Eastman, 1902). In stark contrast to previous depictions of Edestus, the tooth blades curve inward toward the throat presenting an externally streamlined profile of the jaws (Fig. 1B). ...
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Sharks of Late Paleozoic oceans evolved unique dentitions for catching and eating soft bodied prey. A diverse but poorly preserved clade, edestoids are noted for developing biting teeth at the midline of their jaws. Helicoprion has a continuously growing root to accommodate more than 100 crowns that spiraled on top of one another to form a symphyseal whorl supported and laterally braced within the lower jaw. Reconstruction of jaw mechanics shows that individual serrated crowns grasped, sliced, and pulled prey items into the esophagus. A new description and interpretation of Edestus provides insight into the anatomy and functional morphology of another specialized edestoid. Edestus has opposing curved blades of teeth that are segmented and shed with growth of the animal. Set on a long jaw the lower blade closes with a posterior motion, effectively slicing prey across multiple opposing serrated crowns. Further examples of symphyseal whorls among Edestoidae are provided from previously undescribed North American examples of Toxoprion, Campyloprion, Agassizodus, and Sinohelicoprion. The symphyseal dentition in edestoids is associated with a rigid jaw suspension and may have arisen in response to an increase in pelagic cephalopod prey during the Late Paleozoic. This article is protected by copyright. All rights reserved.
... It is useful to compare and contrast the tooth wear observed in Karpinskiprion to that observed in Edestodus (Itano 2015) and Edestus (Itano 2018). These latter two closely related genera are known to possess symphyseal tooth whorls of similar size in both jaws. ...
Restudy of Campyloprion annectans Eastman, 1902 from North America demonstrated that neither specimen included is diagnostic at the species level; thus, the species name is a nomen dubium. Since this species was designated as the type species of the genus, this requires suppression of the generic name also. Another species earlier assigned to Campyloprion, Campyloprion ivanovi Karpinsky, 1924 is used as a type for a newly established genus Karpinskiprion Lebedev et Itano gen. nov. The composition of the family Helicoprionidae Karpinsky, 1911 is reviewed, and a new family Helicampodontidae Itano et Lebedev fam. nov. is erected.Anew specimen of Karpinskiprion ivanovi (Karpinsky, 1924) recently discovered in the Volgograd Region of Russia is the most complete Karpinskiprion specimen ever found. It unambiguously demonstrates the coiled nature of these tooth whorls and presents information on their developmental stages. During organogeny, cutting blades of the crown became reshaped, and basal spurs progressively elongated, forming a grater.Whorl growth occurred by addition of new crowns to the earlier mineralised base followed by later spur growth. In contrast to consistently uniform cutting blades, spurs are often malformed and bear traces of growth interruption. Both sides of the outer coil of the tooth whorl bear lifetime wear facets. The youngest (lingual) crowns are as yetunaffected by wear. The best-preserved facets show parallel radially directed scratch marks. The upper jaw dentition of Karpinskiprion is unknown, but we suggest that the faceted areas resulted from interaction with the antagonistic dental structures here. Three possible hypotheses for this interaction are suggested: (a) two opposing whorls acted as scissor blades, moving alternately from one side to another; (b) the lower tooth whorl fitted between paired parasymphyseal tooth whorls of the opposing jaw; or (c) the lower tooth whorl fitted into a dental pavement in the upper jaw.
... It is possible that the tooth whorl fits entirely inside the oral cavity, as is the case for Sarcoprion (Nielsen 1952). It is also possible that the labial end of the tooth whorl extended outside the oral cavity, as has been hypothesized for Edestus (Itano 2014(Itano , 2015(Itano , 2018. ...
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Campyloprion Eastman, 1902 is a chondrichthyan having an arched symphyseal tooth whorl similar to that of Helicoprion Karpinsky, 1899, but less tightly coiled. The holotype of Campyloprion annectans Eastman, 1902, the type species of Campyloprion, is of unknown provenance, but is presumed to be from the Pennsylvanian of North America. Campyloprion ivanovi (Karpinsky, 1922) has been described from the Gzhelian of Russia. A partial symphyseal tooth whorl, designated as Campyloprion cf. C. ivanovi, is reported from the Missourian Tinajas Member of the Atrasado Formation of Socorro County, New Mexico, USA. Partial tooth whorls from the Virgilian Finis Shale and Jacksboro Limestone Members of the Graham Formation of northern Texas, USA, are designated as Campyloprion sp. Two partial tooth whorls from the Gzhelian of Russia that were previously referred to C. ivanovi are designated as Campyloprion cf. C. annectans. The age of Toxoprion lecontei (Dean, 1898), from Nevada, USA, is corrected from the Carboniferous to the early Permian. An alternative interpretation of the holotype of T. lecontei is presented, resulting in a reversal of its anterior-to-posterior orientation. The genera Helicoprion, Campyloprion, and Shaktauites Tchuvashov, 2001 can be distinguished by their different spiral angles.
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Recent investigations into the Lake Neosho Shale Member of the Altamont Limestone (Desmoinesian, Middle Pennsylvanian) in Montgomery County, Kansas, have yielded a moderately diverse chondrichthyan assemblage. Taxa include teeth of Caseodus eatoni, Edestus cf. E. heinrichi, Petalodus ohioensis, "Cladodus" occidentalis, Lagarodus angustus, Deltodus cf. angularis, the finspine Bythiacanthus sp. and Listracanthus hystrix and Petrodus patelliformis denticles. The Altamont Limestone represents a transgressive-regressive cycle that took place during the Middle Pennsylvanian, and the Lake Neosho Shale Member was deposited in deep water under stagnant, dysaerobic conditions during the highstand phase (maximum transgression).
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In classical theory, teeth of vertebrate dentitions evolved from co-option of external skin denticles into the oral cavity. This hypothesis predicts that ordered tooth arrangement and regulated replacement in the oral dentition were also derived from skin denticles. The fossil batoid ray Schizorhiza stromeri (Chondrichthyes; Cretaceous) provides a test of this theory. Schizorhiza preserves an extended cartilaginous rostrum with closely spaced, alternating saw-teeth, different from sawfish and sawsharks today. Multiple replacement teeth reveal unique new data from micro-CT scanning, showing how the ‘cone-in-cone’ series of ordered saw-teeth sets arrange themselves developmentally, to become enclosed by the roots of pre-existing saw-teeth. At the rostrum tip, newly developing saw-teeth are present, as mineralized crown tips within a vascular, cartilaginous furrow; these reorient via two 90° rotations then relocate laterally between previously formed roots. Saw-tooth replacement slows mid-rostrum where fewer saw-teeth are regenerated. These exceptional developmental data reveal regulated order for serial self-renewal, maintaining the saw edge with ever-increasing saw-tooth size. This mimics tooth replacement in chondrichthyans, but differs in the crown reorientation and their enclosure directly between roots of predecessor saw-teeth. Schizorhiza saw-tooth development is decoupled from the jaw teeth and their replacement, dependent on a dental lamina. This highly specialized rostral saw, derived from diversification of skin denticles, is distinct from the dentition and demonstrates the potential developmental plasticity of skin denticles.
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The paired symphyseal tooth whorls of the Carboniferous chondrichthyan Edestus are perhaps the most enigmatic dental structures of any known vertebrate. The tooth whorls have been compared to scissors or to saw blades. It is commonly held that the tooth whorls were used in opposition, to cut prey caught between them. However, the curvature of the whorls makes such a function inefficient and therefore implausible. A symphyseal tooth of Edestus minor from the Pennsylvanian of Texas provides the first new information bearing on the function of Edestus tooth whorls in over a century. The tooth is truncated apically, and the surface of the surviving portion is worn smooth. The orientation of the abraded surface, perpendicular to the axis of the crown, suggests that the tooth whorls were used to slash prey with a vertical motion of the anterior part of the body. Such a mode of predation apparently has not been reported in any other organism, extinct or extant. In contrast to Edestus, wear to the symphyseal teeth of Helicampodus is to the sides of the crowns, probably resulting from contact with the opposing dentition. Unpublished notes of W. Langston, Jr. (1921–2013) on the interpretation of the Edestus tooth from Texas are discussed.
The first phase in the stepwise collapse of the Carboniferous Coal Forests occurred near the Desmoinesian-Missourian boundary (early Kasimovian, ∼307Ma), and involved extirpation of Lycospora-producing lepidodendrids, and some other lycopsids, across most of tropical Euramerica. In this paper, we follow-up on historical reports of silicified tree-stumps in Peoria County, northwest-central Illinois, USA, which have significant implications for understanding Carboniferous Coal Forest collapse. Rooted near the paleoweathered top of the Lonsdale Limestone, and widespread across an area of ∼250km², the silicified tree-stumps belong to Amyelon-type coniferopsids. A key feature of the fossil wood is the occurrence of abundant axial parenchyma arranged along irregular growth interruptions, suggestive of climatic seasonality, an inference consistent with silicic preservation. The silicified fossil forest directly underlies the Exline Limestone and Athensville Coal, the horizons that mark the US-wide loss of Lycospora, and demonstrate that lowland areas were colonized by dryland coniferopsid forests following Coal Forest collapse. Placed in a cyclothem context, the silicified fossil forest horizon lies above the Maria Creek mudstone paleosol (top of Piasa cyclothem), in which earlier d¹⁸O analyses have identified a major pulse of global warming, and coincides with the 'Hanna City' paleosol (top of Lonsdale cyclothem), which is correlative with the Seminole Sandstone, a Midcontinent incised valley-fill representative of one of the most profound glacioeustatic falls seen in the Pennsylvanian record. Our new findings therefore demonstrate that Coal Forest collapse was closely linked to intensification of glacial cycle amplitude near the Desmoinesian-Missourian boundary, involving both extreme episodes of global warming and cooling.
Potential roles of the rostrum of sawsharks (Pristiophoridae), including predation and self-defence, were assessed through a variety of inferential methods. Comparison of microwear on the surface of the rostral teeth of sawsharks and sawfishes (Pristidae) show that microwear patterns are alike and suggest that the elongate rostra in these two elasmobranch families are used for a similar purpose (predation). Raman spectroscopy indicates that the rostral teeth of both sawsharks and sawfishes are composed of hydroxyapatite, but differ in their collagen content. Sawfishes possess collagen throughout their rostral teeth whereas collagen is present only in the centre of the rostral teeth of sawsharks, which may relate to differences in ecological use. The ratio of rostrum length to total length in the common sawshark Pristiophorus cirratus was found to be similar to the largetooth sawfish Pristis pristis but not the knifetooth sawfish Anoxypristis cuspidata. Analysis of the stomach contents of P. cirratus indicates that the diet consists of demersal fishes and crustaceans, with shrimp from the family Pandalidae being the most important dietary component. No prey item showed evidence of wounds inflicted by the rostral teeth. In light of the similarities in microwear patterns, rostral tooth chemistry and diet with sawfishes, it is hypothesised that sawsharks use their rostrum in a similar manner for predation (sensing and capturing prey) and possibly for self-defence.