Description of the lower jaws of Baculites from the Upper Cretaceous U.S. Western Interior

Abstract We report the discovery of lower jaws of Baculites (Ammonoidea) from the Upper Cretaceous U.S. Western Interior. In the lower Campanian Smoky Hill Chalk Member of the Niobrara Chalk of Kansas, most of the jaws occur as isolated elements. Based on their age, they probably belong to Baculites sp. (smooth). They conform to the description of rugaptychus, and are ornamented with coarse rugae on their ventral side. One specimen is preserved inside a small fecal pellet that was probably produced by a fish. Another specimen occurs inside in a crushed body chamber near the aperture and is probably in situ. Three small structures are present immediately behind the jaw and may represent the remains of the gills. In the lower Maastrichtian Pierre Shale of Wyoming, two specimens of Baculites grandis contain lower jaws inside their body chambers, and are probably in situ. In both specimens, the jaws are oriented at an acute angle to the long axis of the shell, with their anterior ends pointing toward the dorsum. One of the jaws is folded into a U-shape, which probably approximates the shape of the jaw during life. Based on the measurements of the jaws and the shape of the shell, the jaws could not have touched the sides of the shell even if they were splayed out, implying that they could not have effectively served as opercula. Instead, in combination with the upper jaws and radula, they constituted the buccal apparatus that collected and conveyed food to the esophagus.

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Late Cretaceous (Campanian—Maastrichtian) marine reptiles from the Adaffa Formation, NW Saudi Arabia

Geological Magazine ◽

10.1017/s0016756808005062 ◽

2008 ◽

Vol 145 (5) ◽

pp. 648-654 ◽

Cited By ~ 12

Author(s):

B. P. KEAR ◽

T. H. RICH ◽

M. A. ALI ◽

Y. A. AL-MUFARRIH ◽

A. H. MATIRI ◽

...

Keyword(s):

Saudi Arabia ◽

North Africa ◽

Upper Cretaceous ◽

Arabian Peninsula ◽

Detailed Report ◽

Late Mesozoic ◽

Marine Reptiles ◽

Lower Maastrichtian ◽

Marine Reptile ◽

Lower Campanian

AbstractMarine reptile remains occur in the Upper Cretaceous (lower Campanian to lower Maastrichtian) Adaffa Formation of NW Saudi Arabia. This is the first detailed report of late Mesozoic marine reptiles from the Arabian Peninsula. The fossils include bothremydid (cf. Taphrosphyini) turtles, dyrosaurid crocodyliforms, elasmosaurid plesiosaurs, mosasaurs (Prognathodon, plioplatecarpines) and an indeterminate small varanoid. The assemblage is compositionally similar to contemporary faunas from elsewhere in the Middle East/North Africa, and comprises taxa that are typical of the southern margin of the Mediterranean Tethys.

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Encrustation of inarticulate brachiopods on scaphitid ammonites and inoceramid bivalves from the Upper Cretaceous U. S. Western Interior

Acta Geologica Polonica ◽

10.1515/agp-2016-0034 ◽

2016 ◽

Vol 66 (4) ◽

pp. 645-662 ◽

Cited By ~ 4

Author(s):

Neil H. Landman ◽

Joshua S. Slattery ◽

Peter J. Harries

Keyword(s):

Upper Cretaceous ◽

Organic Matrix ◽

Low Oxygen ◽

Soft Body ◽

East Central ◽

Faunal Assemblages ◽

Pierre Shale ◽

Lower Maastrichtian ◽

Faunal Element ◽

Central Montana

AbstractThe inarticulate brachiopodDisciniscais a rare faunal element in the Upper Cretaceous of the U.S. Western Interior. We report two occurrences of encrustation ofDisciniscaon a scaphitid ammonite (scaphite) and several inoceramids from the lower MaastrichtianBaculites baculus/Endocostea typicaBiozones of the Pierre Shale at two localities. Six specimens ofDisciniscaare present on a single specimen ofHoploscaphites crassusfrom east-central Montana. They occur along the furrow at the mature apertural margin. Because the brachiopods are restricted to the margin and do not occur on the rest of the shell, it is likely that they encrusted the ammonite during its lifetime. If so, this implies that the soft body of the scaphite did not cover the outside surface of the aperture, leaving this area vulnerable to epizoan attachment. A total of 13 specimens ofDisciniscaare also present on four specimens ofCataceramus?barabinifrom east-central Wyoming. The brachiopods occur in crevices on the outside of the shells and may have encrusted the inoceramids after their death as the shells began to break down and delaminate, resulting from the decomposition of the organic matrix holding them together. Based on the faunal assemblages at both localities, the presence ofDisciniscamay indicate environments with either low oxygen levels and/or few predators or competitors.

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Nautilid nurseries: hatchlings and juveniles ofEutrephoceras dekayifrom the lower Maastrichtian (Upper Cretaceous) Pierre Shale of east-central Montana

Lethaia ◽

10.1111/let.12222 ◽

2017 ◽

Vol 51 (1) ◽

pp. 48-74 ◽

Cited By ~ 10

Author(s):

Neil H. Landman ◽

James W. Grier ◽

J. Kirk Cochran ◽

Joyce C. Grier ◽

Jack G. Petersen ◽

...

Keyword(s):

Upper Cretaceous ◽

East Central ◽

Pierre Shale ◽

Lower Maastrichtian ◽

Central Montana

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Late Mesozoic—Cenozoic clay mineral successions of southern Iran and their palaeoclimatic implications

Clay Minerals ◽

10.1180/0009855054020165 ◽

2005 ◽

Vol 40 (2) ◽

pp. 191-203 ◽

Cited By ~ 15

Author(s):

F. Khormali ◽

A. Abtahi ◽

H. R. Owliaie

Keyword(s):

Electron Microscopy ◽

Upper Cretaceous ◽

Sedimentary Rocks ◽

X Ray Diffraction ◽

Humid Climate ◽

X Ray ◽

Late Mesozoic ◽

Southern Iran ◽

Transmission Electron

AbstractClay minerals of calcareous sedimentary rocks of southern Iran, part of the old Tethys area, were investigated in order to determine their origin and distribution, and to reconstruct the palaeoclimate of the area. Chemical analysis, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and thin-section studies were performed on the 16 major sedimentary rocks of the Fars and Kuhgiluyeh Boyerahmad Provinces.Kaolinite, smectite, chlorite, illite, palygorskite and illite-smectite interstratified minerals were detected in the rocks studied. The results revealed that detrital input is possibly the main source of kaolinite, smectite, chlorite and illite, whilein situneoformation during the Tertiary shallow saline and alkaline environment could be the dominant cause of palygorskite occurrences in the sedimentary rocks.The presence of a large amount of kaolinite in the Lower Cretaceous sediments and the absence or rare occurrence of chlorite, smectite, palygorskite and illite are in accordance with the warm and humid climate of that period. Smaller amounts of kaolinite and the occurrence of smectite in Upper Cretaceous sediments indicate the gradual shift from warm and humid to more seasonal climate. The occurrence of palygorskite and smectite and the disappearance of kaolinite in the late Palaeocene sediments indicate the increase in aridity which has probably continued to the present time.

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A new species OfTaniwhasaurus(Mosasauridae, Tylosaurinae) from the upper Santonian-lower Campanian (Upper Cretaceous) of Hokkaido, Japan

Journal of Vertebrate Paleontology ◽

10.1671/0272-4634(2008)28[339:ansotm]2.0.co;2 ◽

2008 ◽

Vol 28 (2) ◽

pp. 339-348 ◽

Cited By ~ 20

Author(s):

Michael W. Caldwell ◽

Takuya Konishi ◽

Ikuwo Obata ◽

Kikuwo Muramoto

Keyword(s):

New Species ◽

Upper Cretaceous ◽

A New Species ◽

Lower Campanian

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VI.—Note on Ephippioceras clitellarium, J. de C. Sowerby, sp., and E. costatum, A. H. Foord

Geological Magazine ◽

10.1017/s0016756800183578 ◽

1900 ◽

Vol 7 (12) ◽

pp. 560-561

Author(s):

G. C. Crick

Keyword(s):

New Species ◽

New Genus ◽

British Museum ◽

Acute Angle ◽

The Body ◽

Museum Collection ◽

Body Chamber ◽

Coal Measures ◽

A New Species

The name Nautilus clitellarius was given by J. de C. Sowerby to a Nautiloid from the Coal-measures, Coalbrookdale, Shropshire, and the description was accompanied by three figures, each representing a different specimen. In 1884 the species was included by Professor Hyatt in his new genus Ephippioceras. In 1891 Dr. A. H. Foord found a new species, Ephippioceras costatum, which was said to be “distinguished from E. clitellarium (to which it is, however, very closely related) by the character of the septa and by the surface ornaments. The septa in E. costatum do not form such an acute lobe upon the periphery as do those of E. clitellarium, and they are also a little wider apart in the former species than they are in the latter. Moreover, E. costatum is provided with prominent transverse costæ, which are strongest upon the sides of the shell where they swell out into heavy folds. These costæ are directed obliquely backwards, and cross the septa at an acute angle, passing across the periphery and forming a shallow sinus in the middle. None of the specimens in the British Museum have the test preserved, so that the ribbing has only been observed upon casts. The costæ are equally well developed upon the body-chamber and upon the septate part of the shell in the adult, but they were either very feeble or altogether absent in the young.” A re-examination of the specimens in the Museum collection shows that the separation of the two forms is quite justifiable.

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A lower Maastrichtian (Upper Cretaceous) concentration Lagerstätte of bourgueticrinid crinoids from the Miechów Trough (southern Poland)

Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen ◽

10.1127/njgpa/2016/0552 ◽

2016 ◽

Vol 279 (3) ◽

pp. 239-249 ◽

Cited By ~ 2

Author(s):

Mariusz A. Salamon ◽

Rafał Lach ◽

Anna Wieczorek ◽

Bruno Ferré ◽

Tomasz Brachaniec ◽

...

Keyword(s):

Upper Cretaceous ◽

Southern Poland ◽

Lower Maastrichtian

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Magnetic susceptibility and palaeomagnetic collection of rocks from central and western North Greenland

Rapport Grønlands Geologiske Undersøgelse ◽

10.34194/rapggu.v133.7983 ◽

1987 ◽

Vol 133 ◽

pp. 133-139

Author(s):

N Abrahamsen ◽

R Van der Voo

Keyword(s):

Magnetic Susceptibility ◽

Upper Cretaceous ◽

Crystalline Basement ◽

Mean Values ◽

Si Units ◽

Geometrical Mean ◽

Subsurface Mapping ◽

North Greenland

Some 1900 orientated palaeomagnetic samples were collected from 372 sites in central and western North Greenland in 1985 covering the complete rock sequence from the Precambrian crystalline basement to the Upper Cretaceous dolerite dykes. More than 1100 susceptibility measurements from 91 sites were measured in situ on as many rock units as possibie with susceptibilities above 10-4 SI units. The susceptibilities in the region span 4 orders of magnitude, but the geometrical mean values of major rock groups are well clustered and well defined suggesting that indirect subsurface mapping by aeromagnetic surveying may be a feasible tool for future investigations.

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