Hall Lake Formation


The Hall Lake Formation, formerly called the Hall Lake Member, is a geological formation in Sierra County, New Mexico preserving Lancian fauna, most notably dinosaurs. It is regarded as a member of the McRae Group, including the Elephant Butte and Staton-LaPoint locales.

Description

While most estimates place it firmly within the Lancian fauna, specifically using taxa such as Compsemys as index fossils to recover a Campanian-Maastrichtian age, Lozinsky et al. note the presence of basalt flows and alluvium dating to the Quaternary-Tertiary.
It overlooks the Jose Creek Member and is composed of purple and maroon shales. When they meet, it is marked by a basal conglomerate or a color distinction where conglomerate is absent. Various Cenozoic units overly the formation. Where some choose to classify these layers as a member of the McRae Formation, others classify it as a distinct formation in a group of formations.

Fossil content

Dinosaurs

Saurischians

GenusSpeciesLocalityMaterialNotesImages
Tyrannosauridaeindet.Staton-LaPoint
Lozinsky et al. call it indeterminate
TyrannosaurusT. mcraeensisElephant Butte
  • NMMNH P-3698, a partial skull, lower jaw bones, teeth, and chevrons
    • Alamosaurussp.upper
  • TKM007, a damaged humerus
    		• Tentative referral
    SauropodaPossibly from the Jose Creek Member
    TheropodaPossibly from the Jose Creek Member

    Ornithischians

    TaxonLocalityMaterialNotesImages
    Triceratops sp.2 miles south of Elephant Butte
    • USNM 243, dorsal vertebral centrum
    		This genus, Torosaurus or a novel taxon
    Sierraceratops turneriElephant Butte
  • Partial skeleton with skull
    • CeratopsidaeElephant Butte
  • TKM002, a coranoid
  • TKM020, crest fragment
    		• A new genus similar to Torosaurus is said to exist above the base of the formation
    CeratopsidaeElephant Butte
  • TKM002, a coranoid
  • TKM020, crest fragment
    		• Indeterminate, in abundance
    Torosaurus sp.Elephant Butte ?
    Hadrosauridaecannot be determinedIndeterminate and of unknown origins due to faulting or Quaternary cover
    Ankylosauria
  • TKM011, pyramidal bone fragment
    		• Possibly from the Jose Creek Member, near identical from UNM-FKK-001P of the Kirtland Formation

    Reptiles

    Plants