Localities

The ammonite touch marks that we describe occur in Upper Cretaceous (middle Cenomanian-middle Santonian) deposits of the US Western Interior. There are 27 localities ranging from Montana to New Mexico, representing 14 ammonite range zones (Figs. 18.1-3). Most of the ammonite touch marks are newly documented, although some have previously been reported (Dzulynski and Sanders, 1962: pl. 19B; Mudge, 1972: A68; Scott et al., 1986: Fig. 12f, g).

The ammonite impressions occur in the Dakota Sandstone of western Colorado, the Juana Lopez Member of the Mancos Shale of New Mexico, the Tropic Shale of Utah, the Lincoln and Hartland Members of the Greenhorn Limestone of Colorado, the Turner Sandy Member of the Carlile Shale of South Dakota, the Floweree and Ferdig Members of the Marias River Shale of Montana, the Cody Shale of Wyoming, and the Niobrara Formation of New Mexico. Ammonite touch marks have not been observed from any strata above the middle Santonian.

The localities of the ammonite touch marks are shown in Figs. 18.1-3 and listed below:

1. US Geological (USGS) Mesozoic loc. D2611. South Fork of Sun River, southwest of junction with Bear Creek, sec. 34, T22N, R10W, Lewis and Clark County, Montana. Approximately 110 ft (33 m) above base of Ferdig Member of Marias River Shale (Mudge, 1972).

Fig. 18.1 Map of localities mentioned in the text.

STAGFS AND

WFSTFRN INTFRIOR AMMONITE

WFKTFRN INTFRIOR

1 OCAIITIFS

SUBSTAGES

TAXOM RANGE ZONES

INOCERAMID INTERVAL ZONES

OF TRACES

C

Desmoscaphites bassleri

Sphenoceramus lundbmckensis

<0

Upper

Desmoscaphites erdmannl

tr o

Cltàsçapkltes choteauensts

Cordicerairtus muelbri

c

Middle

COoscaphHas vermiformis

Cordiceramus buettenensis

to CO

Cordiceramus cordiformis

Lower

Çlivscapliites saxitoniarius

Cladocerainus undulùtoplicutus

Upper

Scaphites depressus

Magadiceramus crenetatus

*u

Magadiceramus subquadratus

-<—17,18

Middle

Scaphites mntricosus

yplvicurainus inMutUS

ra

Crvmnoeomnuia crassus crassus

c o

Lower

Scaphites preventrtcosus

Cremnocaramus crassus inconstans

o

Cmmnoceraimis deformis dohrogensis

Cremnoceramus deformis erectus

Scaphites mariasensis

Cremnoceramus waltersdorfensts

Pnonocydus geimnn

Mytitoidos scupini

Upper

Scaphites nigncollensis

Mytitoides mcertus

Scaphites whitfietdi

Inoceramus dakotensis

tnoceramus perptexus

c

Scaphites tarronensis

Inoceramus dimidius

<-27

03

Scaphites warrant

1-

Prionocyctus macombi

Inoceramus alT. dimidius

Middle

Prionocyctus hyatti

tnoceramus howelli

<-12

Colltgnontceras praecox

Inoceramus n sp.

¿sse

Cottignoniceras wuollgan

Mytitoides hercynicus

Mytitoides subharoynicus

Mammitas nodosoid&s

Mytitoides mytiloides

Lower

Vascoceras birchbyt

Mytiloides kossmati

<—22

Pseudaspidoceras tlexuosum

Watinoceras risuonenr.e

Mytiloides puebloerisis

Nigericeras ecottl

Mytitoides tiattiru

Neocardioceras juddii

_

Butroceras clydense

Inoceramus pictus

W Q_

Upper

Euomphaloceras septemsenatum

Vascoœras diartianum

CD

Dunveganoceras condilum

-<—13,15

Dunveganoceras albeflense

Inoceramus ginterensis

<—3

ca E o

Dunveganoceras prohtematicum

-<-14

Duni/aganoceras pondi

inoceramus prefragilis

<—16

Ptesiacanthoceras wyomingense

O

Acanthoceras amphibotum

Inoceramus rutherfordi

<-24

Middle

Acanthoceras bellense

Inoceramus an/anus

<-23

Acanthoceras muldoonense

Acanthncaras granamsansa

Inoceramus eutessanus

Continocaras l&rr&ntense

Fig. 18.2 Biostratigraphic distribution of ammonite touch marks. Numbers on the right side correspond to localities plotted in Fig. 18.1 and mentioned in the text. The chart is reproduced from Cobban et al. (2006).

Fig. 18.3 Map ofMontana showing approximate limits ofthe facies containing scaphitid touch marks in the Ferdig Member of the Marias River Shale. The Xs indicate localities of known touch marks (a single Xmay represent several closely spaced localities).

2. USGS Mesozoic loc. D1493. Barr Creek, SW/ sec. 8, T21N, R8W, Lewis and Clark County, Montana. Ferdig Member of Marias River Shale.

3. USGS Mesozoic loc. D12278. Cone Hill, N/ sec. 13, T22N, R1W, Teton County, Montana. Middle part of Floweree Member of Marias River Shale.

4. USGS Mesozoic loc. D2013. NE/ sec. 22, T23N, R2E, Teton County, Montana. Bed "N" of Ferdig Member of Marias River Shale (Erdmann et al., 1947; Cobban et al., 1976: 45, 47).

5 USGS Mesozoic loc. D2014. NW/ sec. 23, T23N, R2E, Teton County, Montana. Bed "N" of Ferdig Member of Marias River Shale (Erdmann et al., 1947; Cobban et al., 1976: 45, 47).

6. USGS Mesozoic loc. D2019. NW/ sec. 23, T23N, R2E, Teton County, Montana. Approximately 32 ft (9.7 m) above bed "N" of Ferdig Member of Marias River Shale (Erdmann et al., 1947; Cobban et al., 1976: 45, 47).

7. USGS Mesozoic loc. D2254. SW/ sec. 34, T23N, R1W, Teton County, Montana. Approximately 5.5 ft (1.5 m) above bed "N" of Ferdig Member of Marias River Shale (Erdmann et al., 1947; Cobban et al., 1976: 45, 47).

8. USGS Mesozoic loc. D14366. Northern part of Great Falls 7/ minute quadrangle, T23N, R's 2 and 3E, Teton and Chouteau Counties, Montana. Upper part of Ferdig Member of Marias River Shale.

9. USGS Mesozoic loc. D14085. Indian Creek west of Townsend near middle of sec. 6, T6N, R1E, Broadwater County, Montana. Holter Sandstone Member of Marias River Shale (Groff, 1963).

10. USGS Mesozoic loc. D4593. NW/ sec. 9, T9N, R11E, Meagher County, Montana. Carlile Shale.

11. USGS Mesozoic loc. D14088. NW/ sec. 24, T29N, R96W, Fremont County, Wyoming. Cody Shale.

12. USGS Mesozoic loc. D9280. North of Vermillion Creek, NW/ sec. 30, T10N, R100W, Moffat County, Colorado. Basal 10 ft (3 m) of Frontier Sandstone Member of Mancos Shale.

13. USGS Mesozoic loc. D14083. Highway 50, approximately 7 miles (11 km) west of Delta, Delta County, Colorado. Near top of Dakota Formation.

14. USGS Mesozoic loc. D1307. West of Pueblo, near west line of sec. 30, T20S, R65W, Pueblo County, Colorado. Hartland Shale Member of Greenhorn Limestone.

15. USGS Mesozoic loc. D13241. West of Pueblo, NW/ sec. 25, T20S, R66W, Pueblo County, Colorado. Hartland Shale Member of Greenhorn Limestone.

16. USGS Mesozoic loc. D13831. Near center of W/ sec. 25, T20S, R66W, Pueblo County, Colorado. Upper part of Lincoln Member of Greenhorn Limestone.

17. USGS Mesozoic loc. D11309. SE/ sec. 23, T29N, R25E, Colfax County, New Mexico. Sandy Member of Niobrara Formation.

18. USGS Mesozoic loc. D13967. SE/ sec. 8, T17N, R1W, Sandoval County, New Mexico. El Vado Sandstone Member of Mancos Shale.

19. USGS Mesozoic loc. D10590. Sec. 17, T15N, R12W, McKinley County, New Mexico. Mancos Shale.

20. USGS Mesozoic loc. D13101. SW/ sec. 17, T15N, R11W, McKinley County, New Mexico. Near top of Juana Lopez Member of Mancos Shale.

21. USGS Mesozoic loc. D13760. NW/ sec. 14, T40S, R1W, Kane County, Utah. Approximately 175 ft (53 m) below top of Tropic Shale.

22. USGS Mesozoic loc. D11531. Cookes Range, NE/ sec. 13, T21S, R9W, Luna County, New Mexico. Lower part of sandy unit overlying Bridge Creek Limestone Member of Mancos Shale.

23. USGS Mesozoic loc. D10128. Carthage area, NE/ sec. 8, T5S, R2E, Socorro County, New Mexico. Thin-bedded siltstone beds beneath Marker bentonite bed of Mancos Shale.

24. USGS Mesozoic loc. D12744. Riley Canyon, NW/ sec. 21, T18S, R20W, Hidalgo County, New Mexico. Mancos Shale.

25. USGS Mesozoic loc. D5770. NW/ sec. 28, T15N, R12W, McKinley County, New Mexico. Slightly above Bridge Creek Limestone Member of Mancos Shale.

26. USGS Mesozoic loc. D11022. SW/ NE/ sec. 13, T14S, R4W, Sierra County, New Mexico. Shaly siltstone unit 30 feet (9 m) above top of Sciponoceras gracile Zone, Mancos Shale.

27. USGS Mesozoic loc. D12874. NE/ NW/ sec. 36, T7S, R6E, Fall River County, South Dakota. Float from 5-15 ft (1.5-4.6 m) above the base of the Turner Sandy Member of the Carlile Shale.

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