Osteichthyan Lag deposit (Cretaceous to of the United States)

Where: Arkansas (33.7° N, 92.9° W: paleocoordinates 37.7° N, 72.5° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Maastrichtian to Maastrichtian (72.1 - 56.0 Ma)

• Osteichthyan fossils reported here were recovered from a lag deposit separating the uppermost Arkadelphia Formation and basal Midway Group.

Environment/lithology: marine; lithology not reported

• The abundance of osteichthyan teeth, scales

•and skeletal elements, as well as other co-occurring vertebrate

•and invertebrate fossils, indicates the occurrence of a shallow

•marine shelf with fluvial connections at this site.

Size class: macrofossils

Reposited in the AMNH

Collection methods: sieve

• Osteichthyan fossils were collected in the field through both sieving and surface-collecting the lag deposit during times of low water flow in the river. Additionally, deeper areas of the river along cut banks and channels were explored by snorkeling and removal of in situ matrix lag specimens by pry bars, sledge hammers, and chisels. Mesh sizes for sieving in the field ranged from 1.0 to 5.0 mm. Approximately 500 kg of sediment was recovered for laboratory sieve analysis. In the lab, sediment was thoroughly washed through progressively finer-meshed screens ranging from 0.5 to 5.0 mm and dried under heat lamps. Teeth were removed using a magnifying glass and imaged directly with an Olympus SZ61 Binocular Microscope attached to an Infinity-2 Digital Camera. Specimens partially enclosed in matrix (referred to as matrix specimens here) were imaged with a Cannon EOS-30D Digital Camera. Because no new genera or species were identified among the specimens we recovered, abbreviated synonymies are utilized. Specimens described here have been deposited in the fossil fish collections of the American Museum of Natural History (AMNH FF), New York

Primary reference: M. A. Becker, C. S. Mallery, and J. A. Chamberlain. 2010. Osteichthyans from an Arkadelphia Formation–Midway Group lag deposit (Late Maastrichtian–Paleocene), Hot Spring County, Arkansas, U.S.A. Journal of Vertebrate Paleontology 30(4):1019-1036 [M. Bell/M. Bell]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 145187: authorized by Mark Bell, entered by Mark Bell on 28.05.2013

Creative Commons license: CC BY (attribution)

Taxonomic list

 Rhomboganoidei -
Hadrodus cf. priscus Leidy 1857 bony fish
AMNH FF-20322, AMNH FF-20323, and AMNH FF-20324, three branchial teeth.
 Acipenseriformes -
Cylindracanthus ornatus Leidy 1856
AMNH FF-20314, rostral fragment; AMNH FF-20315, rostral fragment in matrix
 Teleostei -
Teleostei indet.
incertae sedis, AMNH FF-20349, seven articulated amphicoelous vertebrae in matrix; AMNH FF-20350, rib bone; AMNH FF-20351 and AMNH FF-20352, two fragmentary tooth plates; AMNH FF-20353 and AMNH FF-20354, two jaw fragments; AMNH FF-20355, isolated tooth.
 Elopiformes - Phyllodontidae
Paralbula casei Estes 1969
AMNH FF-20334, tooth cap; AMNH FF- 20335, pharyngeal tooth plate.
 Salmoniformes - Enchodontidae
Enchodus sp. Agassiz 1843
AMNH FF-20339, AMNH FF-20340, and AMNH FF-20341, three jaw fragments.
Enchodus ferox Leidy 1855
AMNH FF-20336, palatine tooth.
Enchodus gladiolus Cope 1872
AMNH FF-20337, palatine tooth.
 Teleostei -
Beryciformes indet. Regan 1909
incertae sedis, AMNH FF-20345, incomplete opercular bone; AMNH FF-20346 and AMNH FF-20347 two fin spines; AMNH FF-20348, pterygiophore.
Aulopiformes indet. Rosen 1973
incertae sedis. AMNH FF-20342 and AMNH FF-20343, two amphicoelous vertebrae; AMNH FF-20344, neurocranium fragment.
 Neopterygii -
Pycnodontiformes indet. Berg 1937
incertae sedis. AMNH FF-20325 and AMNH FF-20326, two tuberculated skull elements; AMNH FF-20327, AMNH FF-20328, and AMNH FF-20329, three hypochordal elements; AMNH FF-20330, post-cloacal ventral keel scale; AMNH FF- 20331 and AMNH FF-20332, two hypural plates.
 Holostei -
Lepisosteiformes indet. Hay 1929 gar
incertae sedis .AMNH FF-20318, opisthocoelous vertebra inmatrix;AMNHFF-20319 andAMNHFF-20320, two teeth; AMNH FF-20321, skull element.
 Lepisosteiformes - Lepisosteidae
Lepisosteus sp. Agassiz 1843 gar
AMNH FF-20317, ganoid scale.
Atractosteus sp. Rafinesque 1820 gar
AMNH FF-20316, ganoid scale