ArticlePDF Available

On a dentition of Polyrhizodus (Chondrichthyes, Petalodontiformes) from the Namurian bear gulch limestone of Montana

Taylor & Francis
Journal of Verterbrate Paleontology
Authors:
Richard Lund at Saint Joseph's University, Philadelphia, United States
Richard Lund
  • Saint Joseph's University, Philadelphia, United States
Download full-text PDF
Read full-text
Download citation

Abstract and Figures

A partial dentition of Polyrhizodus is described from the Namurian A Bear Gulch Limestone Member, Heath Formation, Big Snowy Group of central Montana. The dentition is interpreted as containing five tooth families in each jaw ramus, with at least three teeth in each family. The dentition is homodont, with teeth decreasing in length as well as numbers of roots in proximal‐distal progression. The teeth conform to those of Polyrhizodus digitatus Leidy, 1857, as well as several other nominal species.The teeth consist of a thin, double‐layered enameloid interdigitating with the underlying osteodentine. Peripheral vascular canals radiate towards the outer surfaces of tooth apexes. Orthodentine is absent. The teeth of Petalodus ohioensis are more derived in that the enameloid is greatly thickened apically and principal vascular canals are limited to vertical rows normal to the cutting edge of the apex.
Figures - uploaded by Richard Lund
Author content
All figure content in this area was uploaded by Richard Lund
Content may be subject to copyright.
Content uploaded by Richard Lund
Author content
All content in this area was uploaded by Richard Lund on Feb 09, 2017
Content may be subject to copyright.
On a Dentition of Polyrhizodus (Chondrichthyes, Petalodontiformes) from the Namurian Bear
Gulch Limestone of Montana
Author(s): Richard Lund
Reviewed work(s):
Source:
Journal of Vertebrate Paleontology,
Vol. 3, No. 1 (Mar., 1983), pp. 1-6
Published by: Taylor & Francis, Ltd. on behalf of The Society of Vertebrate Paleontology
Stable URL: http://www.jstor.org/stable/4522922 .
Accessed: 23/01/2013 10:22
Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .
http://www.jstor.org/page/info/about/policies/terms.jsp
.
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of
content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms
of scholarship. For more information about JSTOR, please contact support@jstor.org.
.
The Society of Vertebrate Paleontology and Taylor & Francis, Ltd. are collaborating with JSTOR to digitize,
preserve and extend access to Journal of Vertebrate Paleontology.
http://www.jstor.org
This content downloaded on Wed, 23 Jan 2013 10:22:45 AM
All use subject to JSTOR Terms and Conditions
This content downloaded on Wed, 23 Jan 2013 10:22:45 AM
All use subject to JSTOR Terms and Conditions
This content downloaded on Wed, 23 Jan 2013 10:22:45 AM
All use subject to JSTOR Terms and Conditions
This content downloaded on Wed, 23 Jan 2013 10:22:45 AM
All use subject to JSTOR Terms and Conditions
W
Y T
X3
Z
FIGURE 3. Polyrhizodus
digitatus
Leidy, MV6167, teeth T-Z in labial view. Scale in cm.
was observed (Herold, 1975), and a distinct
dentinoenameloid junction is present (Fig. 4). Ortho-
dentine is absent, as noted by Radinsky (1961).
The histology of the teeth of Polyrhizodus differs
from that of Petalodus in several particulars. Principal
vascular canals of the core of the crown become limited
to two vertical rows toward the apex, on each side of
and parallel to the cutting edge (Figs. 2, 5-7). The outer
zone of peripheral vascular canals and the depth of the
interdigitating enameloid also thicken dramatically, and
fiber bundles can be seen to extend across the apex of
the crown from one parallel-fibered layer to the other.
A central region (or core) of the apex extends down-
ward and can be seen to have a vertical columnar
structure, the details of which cannot presently be re-
solved. As in Polyrhizodus, however, orthodentine is
absent.
DISCUSSION
The groups of nominal Polyrhizodus species from
Britain and North America seem to differ in one re-
spect, the number of finger-like roots present. The Brit-
ish species are described and illustrated (Davis, 1883)
as varying between 11 and 22 roots, while no described
North American specimen exceeds 11 roots. Among
the nineteen nominal species listed by Hay (1901), all
but P. carbonarius St. John and Worthen (1875) are
Lower Carboniferous and have some distinct asym-
metry. Three species, P. dentatus, P. piasaensis and P.
ponticulus, are not Polyrhizodus but are allied to species
included in Chomatodus by Newberry and Worthen
(1870), while P. truncatus Newberry and Worthen,
1870, lacking divided roots, is a member of the genus
Antliodus (Hansen, written communication). The re-
maining taxa fall roughly into two groups based on
relative proportions of crown height to length. Poly-
rhizodus digitatus Leidy, 1857, as well as a series of
subsequently named teeth listed below, all conform to
the shape and proportions of the teeth in the Bear
Gulch specimen.
Polyrhizodus digitatus Leidy, 1857--Synonyms: P.
princeps Newberry and Worthen, 1866; P. lobatus
Newberry and Worthen, 1866; P. littoni Newberry and
Worthen, 1870; P. amplus St. John and Worthen, 1875;
P. williamsi St. John and Worthen, 1875; P. excavatus
St. John and Worthen, 1875.
Polyrhizodus porosus and the other North American
nominal species have a considerably higher crown in
proportion to the length than does P. digitatus. The
significance of this feature is unknown in the absence
of any information on the opposing dentition of P.
digitatus.
The current specimen provides no evidence of an
association of tooth shapes between Polyrhizodus and
Chomatodus, as suggested by Jaekel (1899). A rela-
tively close relationship between Polyrhizodus, Peta-
lodus and Antliodus is suggested on the basis of tooth
shapes and proportions (Newberry and Worthen, 1866,
1870; Davis, 1883), and it may be suggested that het-
erodonty is probably not present in any of these genera
(Hansen, 1968, on Petalodus). Polyrhizodus has a con-
siderably more primitive tooth histology than does
Petalodus, however. The thickened apical enameloid
and the high relief on the dentinoenameloid junction
may both be considered to confer mechanical stability
of an extreme degree to the teeth of Petalodus (Herold,
1975). This would imply specialization for durophagy
in Petalodus that is not seen in Polyrhizodus. The his-
tology of Antliodus is not known to me.
The absence of orthodentine in these petalodont teeth
contrasts strongly with the condition in all known cla-
dodont, xenacanth, and hybodont (Johnson, 1981)
teeth. Petalodont teeth also contrast with known holo-
cephalians and cochliodonts, which lack enameloid
as well as orthodentine (Radinsky, 1961; Patterson,
1965). The histology of the symphysial teeth of Edestus
(Taylor and Adamec, 1977) is quite similar in the pres-
4 JVP 3(1), March
1983
This content downloaded on Wed, 23 Jan 2013 10:22:45 AM
All use subject to JSTOR Terms and Conditions
.-~~~~ . .xL
Sii
I~~~ ~
,
:J•"
/~~ j. .-
...,
FIGURE
4. Polyrhizodus digitatus
Leidy,
MV6167, transverse section of the apex
of tooth Y1 between crossed
polars.
Lingual
surface
to right.
DEJ, dentinoenameloid
junction. Scale equals 1 mm.
FIGURES 5-7. Petalodus ohioensis, CM41065, Conemaugh
Group, Allegheny County, Pennsylvania.
5, Apex of tooth,
transverse
section. 6, Same in polarized
light, negative reversed. Scale in mm. 7, Apex of tooth, tangential
section, crossed
polars
with gypsum
plate;
lingual
surface to left. Scale equals 1 mm.
ence of enameloid and absence of orthodentine, al-
though the structure of the osteodentine of Edestus is
considerably more varied. The histology of the peta-
lodontid teeth thus adds one more item of evidence to
indicate a relationship with edestoids (and orodon-
toids). This relationship was originally formalized with
the erection of the taxon Bradyodonti (Woodward,
1921; Lund, 1977).
There is no heterodonty in Polyrhizodus, and no
striking evidence, aside from hypothetical transfor-
mation series, of any close relationship between the
Petalodontidae and either Climaxodus or Chomato-
dus. It is thus not possible to confirm the monophyly
of the Petalodontiformes on the basis of the present
evidence.
Acknowledgements-I thank Wendy Lund for tech-
nical support. National Science Foundation grants DEB
77-02548 and DEB 79-19492 supported the research.
REFERENCES
Davis, J. W. 1883. On the fossil fishes of the Carboniferous
Limestone series of Great Britain. Scientific Transac-
tions of the Royal Dublin Society (2)25:327-600.
JVP 3(1), March 1983 5
This content downloaded on Wed, 23 Jan 2013 10:22:45 AM
All use subject to JSTOR Terms and Conditions
Hansen, M. C. 1968. The Upper Paleozoic genus Petalodus
(Bradyodonti) from North America. Proceedings of the
Nebraska Academy of Sciences, April 26-27; abstract.
Hay, O. P. 1901. Bibliography and Catalogue of the Fossil
Vertebrata of North America. Bulletin of the United
States Geological Survey 179:868 pp.
Herold, R. C. B. 1975. Scanning electron microscopy of
enameloid and dentine in fish teeth. Archives of Oral
Biology 20:635-640.
Jaekel, 0. 1899. Ueber die Organization der Petalodonten.
Zeitschrift der Deutschen geologischen Gesellschaft 51:
258-297; Berlin.
Johnson, G. D. 1981. Hybodontidae (Chondrichthyes) from
the Wichita-Albany Group (Early Permian) of Texas.
Journal of Vertebrate Paleontology 1(1):
1-41.
Kerebel, B., Le Cabellec, M. T., Daculsi, G. and Kerebel,
L. M. 1978. Osteodentine and vascular osteodentine
of Anarhichas lupus (L.). Cell and Tissue Research 187:
135-146.
Leidy, J. 1857. Descriptions of the remains of fishes from
the Carboniferous Limestone of Illinois and Missouri.
Transactions of the American Philosophical Society 11:
87-90.
Lund, R. 1977. New information on the evolution of the
bradyodont Chondrichthyes. Fieldiana: Geology 33(28):
521-539.
1977. A new petalodont (Chondrichthyes, Brad-
yodonti) from the Upper Mississippian of Montana. An-
nals of Carnegie Museum 46(10): 129-155.
Malzahn, E. 1968. Uber neue Funde von Janassa bitu-
minosa (Schloth.) im nieder rheinischen Zechstein. Geo-
logisches Jahrbuch 85:67-96; Hannover.
Newberry, J. S. 1897. New species and a new genus of
American Paleozoic Fishes, together with notes on the
genera Oracanthus, Dactylodus, Polyrhizodus, Sanda-
lodus, Deltodus. Transactions of the New York Academy
of Sciences 16:282-303 + 3 pls.
- and Worthen, A. H. 1866. Descriptions of new
species of vertebrates, mainly from the Subcarbonifer-
ous Limestone and Coal Measures of Illinois. Geological
Survey of Illinois 2:9-131.
I
and 1870. Descriptions of fossil verte-
brates. Geological Survey of Illinois 4:347-374.
Orvig, T. 1966. Histologic studies of ostracoderms, plac-
oderms and fossil elasmobranchs. 2. On the dermal skel-
eton of two late Paleozoic elasmobranchs. Arkiv fdr
Zoologi 19:1-30 + 5 pls.
1967. Phylogeny of tooth tissues: Evolution of
some calcified tissues in early vertebrates. In Miles, A.
E. W. (ed.), Structural and Chemical Organization of
Teeth, Vol. 1:45-110. Academic Press, London.
Patterson, C. 1965. The phylogeny of the chimaeroids.
Philosophical Transactions of the Royal Society of Lon-
don (B) 249(757):101-219.
Radinsky, L. 1961. Tooth histology as a taxonomic crite-
rion for cartilaginous fishes. Journal of Morphology
109(1):73-92.
Reif, W. E. 1973. Morphologie und Ultrastruktur des Hai
"Schmelzes". Zoologica Scripta 2:231-250.
Shellis, R. P. and Berkovitz, B. K. B. 1980. Dentine struc-
ture in the rostral teeth of the sawfish Pristis (Elasmo-
branchii). Archives of Oral Biology 25:339-343.
St. John, O. H. and Worthen, A. H. 1875. Descriptions of
fossil fishes. Geological Survey of Illinois 6:245-488.
Taylor, K. and Adamec, T. 1977. Tooth histology and ul-
trastucture of a Paleozoic shark, Edestus heinrichii.
Fieldiana: Geology 33:441-470.
Woodward, A. S. 1921. Observations on some extinct elas-
mobranch fishes. Proceedings of the Linnean Society of
London, Sess. 133, pp. 29-39.
1889. Catalogue of the Fossil Fishes in the British
Museum. Part. I. Elasmobranchii. Taylor & Francis,
London, 474 pp.
6 JVP 3(1). March 1983
This content downloaded on Wed, 23 Jan 2013 10:22:45 AM
All use subject to JSTOR Terms and Conditions
... The petalodonts are Permo Carboniferous chon drichthyan fishes described principally on the basis of isolated teeth and for which the Petalodus form tooth is generally considered representative. Complete to partial petalodont dentitions have been limited (Han cock and Howse, 1870;Jaekel, 1899;Hansen, 1985;Lund, 1983Lund, , 1989Brandt, 1996;Zangerl, 1981 andGinter et al., 2010) and incomplete to entirely holo morphic material is rarer still (Jaekel, 1899, Schaum berg, 1979, Lund, 1989. ...
... Smooth pebble like structures are seen in Obruchevodus griffithi and similar structures have been reported for J. bituminosa (Han cock and Howse's smooth tubercles of Plate X Fig 8). We postulate that these may represent enlarged denti cles of the oral margin, as other petalodonts also show squamation to rim the bases of tooth families and con tinue into the surrounding matrix (e.g., Polyrhizodus digitatus Leidy as described by Lund, 1983, and J. bituminosa as described by Hancock and Howse, 1870). One as yet undescribed Bear Gulch specimen (CM 62710) also demonstrates specialized denticles to be borne by the branchial apparatus. ...
A New Petalodont Chondrichthyan from the Bear Gulch Limestone of Montana, USA, with Reassessment of Netsepoye hawesi and Comments on the Morphology of Holomorphic Petalodonts
Article
Full-text available
  • Dec 2014
A new holomorphic petalodont from the Bear Gulch Limestone, Obruchevodus griffithi, is described and features of the related Netsepoye hawesi are reinterpreted. Comparison of these taxa with the holomorphic petalodonts Janassa bituminosa, Belantsea montana, and Siksika ottae provide insight into pet� alodont anatomical form and variation. All holomorphic material supports holostyly and nested, subcranial branchial arches. Teeth occur in families with linguo�labial replacement but alignment of most families rela� tive to the jaw ramus results in a staggered tooth alignment between adjacent tooth families. Symphysial teeth are the exception to this pattern. Tooth retention is clearly indicated only in the homodont Janassa bitumi� nosa. In contrast there is no evidence of tooth retention in examined petalodonts with a heterodont dentition. There is variation in styles of squamation among all forms; sexual dimorphism in scale development and dis� tribution are suggested as well. Despite depressiform and compressiform conditions there is commonality in possession of a lobular, anteriorly extended and high aspect ratio pectoral fin, large pelvic fins, and absence of fin spines. Pectoral fins provide the primary means of locomotion. Variation in the ventral aspect of the pel� vic girdle anatomy exists between that interpreted for Janassa and that documented by Obruchevodus and Netsepoye. Male claspers are long and highly flexible. Laterally compressed body forms display two dorsal fins (first being largest) that are variable in their vertical expanse along the length of the fin. Cranial anatomy shows some correspondence to general features of the Holocephali. Meckel’s cartilage is dorso�ventrally deep, as in extant chimaeroids, with contralaterals in symphysial fusion. Mandibular labial cartilages, when present, may be sexually dimorphic
View
... Fissodus style teeth are found as the lower median tooth position of most heterodont dentitions, with a Ctenoptychius like upper anterior tooth or teeth, accompanied by lateral upper and lower teeth of Janassa like form. As hetero donty seems to have been the plesiomorphic condition not only in these petalodonts but for the Euchondro cephali as well, a model is proposed to explain the derived homodont conditions found in Petalodus (Hansen, 1985), Polyrhizodus (Lund, 1983), Belantsea (Lund, 1989, and J. bituminosa (Jaekel, 1899). The principally dentition based cladistic analysis retains the previously erected families Petalodontidae, Belantseidae, and Jan assidae, rejects the assignment of "J." korni to Janassa, and suggests a heterodont clade for the remaining taxa. ...
... Pet alodus ohioensis is homodont. The type species of Polyrhizodus, P. magnus (McCoy, 1848) is represented only by isolated teeth, but a unique specimen of Polyrhizodus digitatus bears five tooth families on a ramus (Lund, 1983). Polyrhizodus digitatus is homo dont with slight size and shape changes along the jaw; its teeth are of the Petalodus form. ...
On the Relationships of the Petalodontiformes (Chondrichthyes)
Article
Full-text available
  • Dec 2014
The Petalodontiformes are Upper Paleozoic marine euchondrocephalan chondrichthyans known primarily from isolated teeth. Few dentitions have been reported, among them that of the Permian Janassa bituminosa and “Janassa” korni and the Serpukhovian, Mississippian Belantsea montana, Obruchevodus grif� fithi, Netsepoye hawesi and Siksika ottae. A dentition has been reconstructed for the Pennsylvanian Petalodus ohioensis. New information on dentitions and postcranial morphology is now introduced for petalodont remains from the Bear Gulch Limestone of Montana (USA). These include N. hawesi, Petalorhynchus bear� gulchensis, several specimens bearing teeth of the Fissodus form, and a new genus and species, Fissodopsis robustus. Analysis of all material reveals dignathic heterodonty as prevalent among the Upper Mississippian petalodonts, with distinct regionalization resulting in large anterior and small lateral teeth. Fissodus�style teeth are found as the lower median tooth position of most heterodont dentitions, with a Ctenoptychius�like upper anterior tooth or teeth, accompanied by lateral upper and lower teeth of Janassa�like form. As hetero� donty seems to have been the plesiomorphic condition not only in these petalodonts but for the Euchondro� cephali as well, a model is proposed to explain the derived homodont conditions found in Petalodus (Hansen, 1985), Polyrhizodus (Lund, 1983), Belantsea (Lund, 1989), and J. bituminosa (Jaekel, 1899). The principally dentition�based cladistic analysis retains the previously erected families Petalodontidae, Belantseidae, and Jan� assidae, rejects the assignment of ”J.” korni to Janassa, and suggests a heterodont clade for the remaining taxa. Two new families are designated on the basis of these data, the Petalorhynchidae and the Obruchevodidae.
View
... The dental arrangements of janassids and other petalodonts have been proposed based on articulated or nearly articulated specimens that show the tooth family positions (Hancock and Atthey 1869;Hancock and Howse 1870;Jaekel 1898Jaekel , 1899Woodward 1919;Schaumberg 1979;Lund 1984Lund , 1989Brandt 1996Brandt , 2009Grogan et al. 2014;Lund et al. 2014). The first reconstructions of janassid dentitions for Janassa linguaeformis (Atthey 1868;Hancock and Atthey 1869) and Janassa bituminosa (Hancock and Howse 1870) in which the authors reconstructed the dental series with symphyseal tooth family flanked by three laterals families on either side are based on associated but distorted dentitions of both taxa. ...
Janassid petalodonts (Chondrichthyes, Petalodontiformes, Janassidae) from the middle Mississippian (Viséan) Ste. Genevieve Formation, Mammoth Cave National Park, Kentucky, USA
Article
Full-text available
Isolated teeth of two janassid petalodonts collected from cave passages within the Middle Mississippian (Viséan) Joppa Member of the Ste. Genevieve Formation at Mammoth Cave National Park, Kentucky represents the first record of this group of chondrichthyans from this formation. A new janassid, Strigilodus tollesonae, gen et sp. nov., is recognised from isolated teeth, representing all tooth families, and are characterised by their rounded spoonlike cusps and V- to U-shaped lingual cristae. Janassa sp. is also present within the Joppa Member of the Ste. Genevieve Formation. Dental reconstructions are proposed for Strigilodus tollesonae and Cypripediodens cristatus, modelled after previous observations for Janassa dentitions. Strigilodus had a dental arrangement more similar to Janassa, while Cypripediodens was uniquely adapted for a possible extreme form of durophage feeding. We propose that within Janassidae, there were two unnamed subfamilies with Janassa and Strigilodus forming the Janassinae, while Cholodus, Cypripediodens, and Cavusodus forming Cholodinae subfam. nov.
View
... The tooth fragment consists of a labiolingually flattened cusp with an asymmetric, triangular tip. The asymmetric nature of this tooth fragment eliminates petalodont taxa that tend to have symmetrical crowns in all tooth families such as Petalodus, Belantsea, and Polyrhizodus (Lund, 1983(Lund, , 1989, or symmetric upper symphysial teeth as in Petalorhynchus, Siksika, Orbuchevodus, Fissodopsis, and Netsepoye (Lund, 1989;Grogan et al., 2014;Lund et al., 2014). This fragment could represent the lower Fissodus-like symphysial tooth morph, recently recognized in a majority of petalodonts from Bear Gulch, which consists of a bifurcated and mesiodistally expanded crown . ...
Carboniferous chondrichthyan assemblages from the Surprise Canyon and Watahomigi formations (latest Mississippian-Early Pennsylvanian) of the western Grand Canyon, Northern Arizona
Article
Full-text available
  • Dec 2018
Two chondrichthyan assemblages of Late Mississippian/Early Pennsylvanian age are now recognized from the western Grand Canyon of northern Arizona. The latest Serpukhovian Surprise Canyon Formation has yielded thirty-one taxa from teeth and dermal elements, which include members of the Phoebodontiformes, Symmoriiformes, Bransonelliformes, Ctenacanthiformes, Protacrodontoidea, Hybodontiformes, Neoselachii (Anachronistidae), Paraselachii (Gregoriidae, Deeberiidae, Orodontiformes, and Eugeneodontiformes), Petalodontiformes, and Holocephali. The euselachian grade taxa are remarkably diverse with four new taxa recognized here; the Protacrodontidae: Microklomax carrieae new genus new species and Novaculodus billingsleyi new genus new species, and the Anchronistidae: Cooleyella platera new species and Amaradontus santucii new genus new species The Surprise Canyon assemblage also has the youngest occurrence of the elasmobranch Clairina , previously only known from the Upper Devonian. The Surprise Canyon Formation represents a nearshore fluvial infilling of karstic channels, followed by a shallow marine bioherm reef, and finally deeper open water deposition. The early Bashkirian Watahomigi Formation represents open marine deposition and contains only two taxa: a new xenacanthiform, Hokomata parva new genus new species, and the holocephalan Deltodus . The relationship between the Surprise Canyon and Watahomigi chondrichthyan assemblages and other significant coeval chondrichthyan assemblages suggests that there may have been eastern and western distinctions among the Euamerican assemblages during the Serpukhovian due to geographic separation by the formation of Pangea. UUID: http://zoobank.org/54a906b6-4873-4f84-92b5-ca0752de01aa
View
... The tooth fragment consists of a labiolingually flattened cusp with an asymmetric, triangular tip. The asymmetric nature of this tooth fragment eliminates petalodont taxa that tend to have symmetrical crowns in all tooth families such as Petalodus, Belantsea, and Polyrhizodus (Lund, 1983(Lund, , 1989, or symmetric upper symphysial teeth as in Petalorhynchus, Siksika, Orbuchevodus, Fissodopsis, and Netsepoye (Lund, 1989;Grogan et al., 2014;Lund et al., 2014). This fragment could represent the lower Fissodus-like symphysial tooth morph, recently recognized in a majority of petalodonts from Bear Gulch, which consists of a bifurcated and mesiodistally expanded crown . ...
Carboniferous chondrichthyan assemblages from the Surprise Canyon and Watahomigi formations (latest Mississippian-Early Pennsylvanian) of the western Grand Canyon, Northern Arizona
Article
Full-text available
  • Sep 2018
Two chondrichthyan assemblages of Late Mississippian/Early Pennsylvanian age are now recognized from the western Grand Canyon of northern Arizona. The latest Serpukhovian Surprise Canyon Formation has yielded thirty-one taxa from teeth and dermal elements which include members of the Phoebodontiformes, Symmoriiformes, Bransonelliformes, Ctenacanthiformes, Protacrodontoidea, Hybodontiformes, Neoselachii (Anachronistidae), Paraselachii (Gregoriidae, Deeberiidae, Orodontiformes, and Eugeneodontiformes), Petalodontiformes, and Holocephali. The euselachian grade taxa are remarkably diverse with four new taxa recognized here; the Protacrodontidae: Microklomax carrieae n. gen. n. sp. and Novaculodus billingsleyi n. gen. n. sp., and the Anchronistidae: Cooleyella platera n. sp. and Amaradontus santucii n. gen. n. sp. The Surprise Canyon assemblage also has the youngest occurrence of the elasmobranch Clairina, previously only known from the Upper Devonian. The Surprise Canyon Formation represents a nearshore fluvial infilling of karstic channels, followed by a shallow marine bioherm reef, and finally deeper open water deposition. The early Bashkirian Watahomigi Formation represents open marine deposition and contains only two taxa: a new xenacanthiform, Hokomata parva n. gen. n. sp., and the holocephalan Deltodus. The relationship between the Surprise Canyon and Watahomigi chondrichthyan assemblages and other significant coeval chondrichthyan assemblages suggest that there may have been eastern and western distinctions between the Euamerican assemblages during the Serpukhovian due to geographic separation by the formation of Pangea.
View
... Discussion--Teeth of Petalodus are often the most common chondrichthyan fossils reported from the Pennsylvanian and Permian rocks of eastern Kansas (Leidy, 1859;Miller, 1957;Miller and Mann, 1958;Chorn and Conley, 1978;Robb, 2003). Although associated tooth sets have not been found in Kansas, complete dentitions from other petalodonts have been described (Lund, 1977(Lund, , 1983(Lund, , 1989). The body shape of petalodonts appears to have varied, with some taxa having laterally compressed bodies (active, freeswimming; see Lund, 1989), and others having a more batoid-like, dorsoventrally compressed body (bottom dwelling; see Zangerl, 1981). ...
MIDDLE PENNSYLVANIAN (DESMOINESIAN) CHONDRICHTHYANS FROM THE LAKE NEOSHO SHALE MEMBER OF THE ALTAMONT LIMESTONE IN MONTGOMERY COUNTY, KANSAS
Article
Full-text available
  • Apr 2005
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).
View
... Apresentavam dentes sinfisiais que davam à boca do peixe o aspecto de "bico de papagaio" (Toledo, 2001). Eram semelhantes às raias atuais, com corpo achatado dorso-ventralmente (Figura 5) e se locomoveram lentamente no fundo do mar próximo à costa (Lund, 1977a(Lund, ,1977b(Lund, ,1983Nelson, 1994;Ragonha, 1978;Toledo, 2001). Por essa razão os petalodontes são bons indicadores de paleoambiente marinho (Ragonha, 1978). ...
View
VERTEBRATE PALEONTOLOGY OF MONTANA
Chapter
Full-text available
  • Nov 2020
Montana is renowned for its rich paleontological treasures, particularly those of vertebrate animals such as fishes, dinosaurs, and mammals. For example, the most speciose fish fauna in the world comes from Fergus County. The first dinosaur remains noted from the western hemisphere came from an area near the mouth of the Judith River in what would become Fergus County. The first Tyrannosaurus rex skeleton, and many more since, have come from Garfield and McCone Counties. The first dinosaur recognized to show the relationship between dinosaurs and birds came from Carbon County, and the first dinosaur eggs, embryos, and nests revealing dinosaur social behav- iors were found in Teton County. The first dinosaur confirmed to have denned in burrows was found in Beaverhead County. Although Montana is not often thought of for mammal fossils, a great diversity of late Mesozoic and Cenozoic mammals also occurs within the State. Especially noteworthy are the mid to Late Cretaceous primitive mammals found within the great dino- saur-producing formations of eastern Montana, the early and late Paleocene mammals of the Fort Union Formation in central and eastern Montana, and the late Eocene/early Oligocene deposits in southwestern Montana. Additionally, middle Eocene and middle Miocene strata contain important mammal fossils, in some cases representing unique occurrences. This chapter highlights Montana’s most significant vertebrate fossils, and the environments in which the animals lived and died. We have chosen to list representative Holotypes, and taxa that have been formally described in the literature, rather than listing all of the species reported in “faunal lists,” since these lists often contain very fragmentary remains, and only best guesses of their identities. The taxa listed here are what we consider to be the most representative, from which important and interesting hypotheses have been derived concerning the evolution, behavior, and paleoecology of vertebrate fossil taxa from Montana. All Paleozoic vertebrates from Montana come from marine sediments, whereas the Mesozoic assemblages are derived from transgressive–regressive alternating marine and freshwater deposits, and the Cenozoic faunas are derived strictly from freshwater terrestrial environments.
View
Paleontologia de vertebrados da transição entre os grupos Tubarão e Passa Dois (neopaleozóico) no centro-leste do Estado de São Paulo
Thesis
Full-text available
  • Jun 2007
A good part of the Neopaleozoic section of the Paraná basin is well-exposed in central-east Sao Paulo, Brazil, represented by sedimentary rocks of the Tubarão Group (Itararé Subgroup and Tatuí Formation) and the Passa Dois Group (Irati and Corumbataí formations). Between Leme and Capivari and in the area of the Pitanga Dome, between Piracicaba and Ipeúna, the transition between the Tatuí and Irati formations commonly is characterized by abundantly fossiliferous, poorly sorted, relatively coarse sandstones (sandstones with granules, conglomeratic sandstones and conglomerate) in abrupt contact with silty shale of the Irati Formation. The present work concentrated on the study of Palaeozoic palaeovertebrates and their significance for paleontological, sedimentological and stratigraphical interpretations of the transition between the Tubarão and Passa Dois groups. The identified fossil content consists of scales, teeth and bony parts from several types of fish, from fresh and salt water, as well as from possible tetrapods. Chondrichthyes are represented by two varieties of cladodont teeth; several types of teeth of the xenacanth ?Pleuracanthus? albuquerquei Silva Santos, 1946; teeth of Orodontiformes; teeth of two species of Petalodontiformes, the first, and more common, Itapyrodus punctatus Silva Santos, 1990, and the other, represented by a single specimen, an unidentified species. The material also includes a fin spine of an adult Ctenacanthiformes and a possible placoid scale. The fauna of Osteichthyes is more abundant, being composed of teeth and ganoid scales of Paleonisciformes and cosmoid scales of Actinistia. Also observed are large labyrinthodont teeth (from primitive tetrapods and/or rhipidistid fish) and bony parts attributed to fish and/or possible amphibians. The fossils are usually disarticulated and dispersed and the bony elements fragmented and abraded. Even so, teeth of continental animals - labyrinthodonts and Xenacanthiformes, were found with different types of preservation, which is indicative of a fluvial influence. The mixture of marine elements, like petalodonts, and continental elements suggests a nearshore character with a strong continental influence for the transition between the units. Taphonomic studies suggest that the studied layer is a residual (lag) deposit that resulted directly from reworking by waves. Thus, the Tatuí - Irati transition is part of the depositional evolution of the early Irati Formation. It is therefore suggested that the transition be recognized as a local basal facies of this formation of great paleontological and stratigraphical importance in the central-eastern part of the state of Sao Paulo.
View
View
View
View
View
View
View
View
View
View
View
Hybodontoidei (Chondrichthyes) from the Wichita-Albany Group (Early Permian) of Texas
Article
  • Jun 1981
Nearly 4000 hybodontoid teeth assignable to the typically Mesozoic genera Acrodus and Polyacrodus were recovered by bulk-sampling techniques from the Early Permian Wichita-Albany Group in north-central Texas. They belong to 37 local faunas. Generic assignments are based mainly on crown histology, following the methods of earlier workers. This approach must suffice until the suborder can be revised using a new methodology, yet to be devised. The roots of all the teeth bear specialized foramina on the labial side, parallel to the root-crown contact. The teeth questionably assigned to Acrodus have roots morphologically different from those of Mesozoic species. Hybodus is absent. Tooth morphotypes are assigned to six new species: ?A. olsoni (large teeth with symmetrical crowns; dentition moderately hetero-dont), ?A. sweetlacruzensis (arcuate root-crown contact; roots with deep, closed sulcus; dentition tion homodont), P. zideki (teeth small; crowns uncrenulated, possess longitudinal and transverse occlusal crests, and prominent labial and lingual processes; dentition moderately heterodont), P. lapalomensis (crowns asymmetrical; roots with open sulcus which has straight margins; dentition homodont), P. ritchiei (crowns longitudinally asymmetrical, with a double longitudinal occlusal crest; roots flexed and lingually extended; dentition considerably heterodont), and P. wichitaensis (crowns with posteriorly directed, asymmetrical principal cusp and posterior accessory cusps; histology variable; roots extended lingually; dentition strongly heterodont). All these species, except possibly P. lapalomensis and P. ritchiei, also occur in the Late Pennsylvanian of Nebraska. Hybodontoid cephalic spines and dorsal fin spines accompany the teeth, but cannot be safely assigned to any of the taxa.
View