Medicine Rocks Site 1 (Paleocene of the United States)

Also known as Medicine Rocks I

Where: Carter County, Montana (46.1° N, 104.5° W: paleocoordinates 51.8° N, 81.0° W)

• coordinate stated in text

• outcrop-level geographic resolution

When: Ekalaka Member (Fort Union Formation), Torrejonian (63.3 - 61.7 Ma)

• "The Medicine Rocks Sandstone, a unit that was originally mapped as part of the Tongue River Member of the Fort Union Formation. More recent work, however, has shown that the Medicine Rocks Sandstone is bounded by unconformities and it has thus been designated as its own unit, now called the Ekalaka Member of the Fort Union Formation YPM PU 16781 is from “Locality 1,” which Sloan (1970) grouped with other localities into an assemblage named Medicine Rocks I. A tentative Torrejonian 3 age is typically given on the basis of the mammalian assemblage found at that site (e.g., Lofgren et al. 2004)" (Joyce et al. 2009)

Environment/lithology: terrestrial; sandstone

• "freshwaters of a warm temperate coastal plain" (Estes 1976)
• "sandstone" (Estes 1976)

Size class: mesofossils

Collection methods: surface (float)

Primary reference: R. Estes. 1976. Middle Paleocene lower vertebrates from the Tongue River Formation, southeastern Montana. Journal of Paleontology 50(3):500-520 [J. Alroy/J. Alroy]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 14874: authorized by John Alroy, entered by John Alroy on 30.04.1994, edited by Philip Mannion, Patricia Holroyd and Matthew Carrano

Creative Commons license: CC BY (attribution)

Taxonomic list

• said to be To3
several other localities in this area are Tiffanian
Site III and Mehling Site are "at essentially the same stratigraphic level": Krause 1987a
possibly relevant: Pantolambda bathmodon Simons 1960: "probably occurs in the Medicine Rocks local fauna" Pantolambda cavirictum Simons 1960: "Medicine Rock local fauna"
SEE Sloan 1970
Chondrichthyes
 Myliobatiformes - Dasyatidae
Dasyatidae indet. Jordan 1888 whiptail stingray
Actinopteri
 Acipenseriformes - Polyodontidae
cf. Paleopsephurus sp. MacAlpin 1947 paddlefish
 Acipenseriformes - Acipenseridae
cf. Acipenser sp. Linnaeus 1758 sturgeon
 Amiiformes - Palaeolabridae
 Amiiformes - Amiidae
Amia fragosa Jordan 1927 bowfin
Amia uintaensis Leidy 1873 bowfin
 Lepisosteiformes - Lepisosteidae
Osteichthyes
 Proteida - Batrachosauroididae
Opisthotriton kayi Auffenberg 1961 salamander
 Caudata - Urodela
Habrosaurus dilatus Gilmore 1928 siren
Scapherpeton tectum Cope 1876 salamander
Lisserpeton bairdi Estes 1965 salamander
Reptilia
 Testudines -
Compsemys victa Leidy 1856 turtle
 Testudines - Baenidae
Palatobaena bairdi2 Gaffney 1972 turtle
CCM 77-11 (three-quarters of undistorted skull)
 Testudines - Pantrionychidae
Hutchemys rememdium n. gen. n. sp.4 Joyce et al. 2009 turtle
YPM PU 16795 - holotype (a nearly complete postcranial skeleton); referred specimen: YPM PU 16781 (right hyo/hypoplastron)
cf. Plastomenus sp. Cope 1873 turtle
 Loricata -
Crocodylia indet.1 crocodilian
 Crocodylia - Alligatoridae
Alligatorinae indet. Cuvier 1807 crocodilian
 Squamata - Xenosauridae
Exostinus lancensis Gilmore 1928 squamates
PU 16780, anterior end of left maxilla
 Squamata - Necrosauridae
cf. Provaranosaurus sp. Gilmore 1942 squamates
PU 16779a–e, broken left maxilla with two teeth, fragment of left maxilla with one tooth, fragment of left dentary with no teeth preserved, fragment of right dentary with one tooth. PU 16782, posterior end of right dentary with one tooth.
 Squamata - Anguidae
cf. Gerrhonotus sp., "Pancelosaurus piger" = Odaxosaurus piger
cf. Gerrhonotus sp. Wiegmann 1828 alligator lizard
PU 16778a, almost complete right dentary; 16778b, posterior half of left dentary. Unnumbered fragments of three right and three left dentaries; one questionably referred posterior half of left dentary.
"Pancelosaurus piger" = Odaxosaurus piger Gilmore 1928 squamates
PU 17034, posterior ends of two right and three left dentaries, the anterior end of a left maxilla, and one tooth bearing fragment. Numerous unnumbered osteoscutes, complete and partly co-ossified frontals, and another frontal fragment.
 Squamata -
cf. Coniophis precedens6 Marsh 1892 snake
PU 16773, nine vertebrae, most of them eroded and broken
cf. Coniophis precedens6 Marsh 1892 snake
PU 16774, eleven eroded and broken vertebrae.
 Squamata - Globauridae
Contogenys ekalakaensis n. sp.8 Nydam and Fitzpatrick 2009 lizard
YPM-PU 17035, right dentary; 17036a, broken left dentary; 17036b, post. end of right dentary with associated coronoid, splenial, and parts of surangular and angular
 Squamata - Oligodontosauridae
Oligodontosaurus cf. wyomingensis7 Gilmore 1942 worm lizard
PU 18577, almost complete trunk vertebra; 16777, posterior part of right dentary.
 Squamata - Xantusiidae
Palaeoxantusia fera Hecht 1956 night lizard
PU 16775, complete right dentary; 16776, posterior part of left dentary with associated angular and part of surangular; three other unnumbered fragments of dentaries, two left, one right.
 Choristodera -
Champsosaurus sp. Cope 1876 choristodere
Mammalia
 Primates - Plesiadapidae
Pronothodectes cf. matthewi3 Gidley 1923 primate
 Primates - Picrodontidae
Picrodus silberlingi10 Douglass 1908 primate
 Primates - Carpolestidae
Elphidotarsius cf. florencae9 Gidley 1923 primate
 Ungulata - Phenacodontidae
Tetraclaenodon puercensis12 Cope 1881 condylarth
 Multituberculata - Neoplagiaulacidae
Parectypodus sylviae11 Rigby 1980 multituberculate
Mesodma pygmaea11 Sloan 1987 multituberculate
 Multituberculata - Ptilodontidae
Baiotomeus lamberti n. sp.5 Krause 1987 multituberculate