Table 1. Radiometric date recalibrations.
| Formation | Stratigraphic height | Published | Recalibrated | Source Publication | Notes | ||||
|---|---|---|---|---|---|---|---|---|---|
| FCs age | Age | Error | FCs age | Age | Error | ||||
| Judith River | Unit 1 of Oldman Formation, 31.8 m above top of Marker A Coal of Taber Coal Zone | 27.84* | 78.2 | 0.2 | 28.305 | 79.49 | 0.21 | Goodwin and Deino, 1989 | Upper Kennedy Coulee, equivalent to Unit 1 of Oldman Formation. Sanidine. *Original standard used was MMhb-1 = 520.4 +/- 1.7 Ma, which was equivalent to FCs = 27.84 (Renne et al., 1998). |
| Judith River | Taber Coal Zone of Foremost Formation, 4.8 m below top of Marker A Coal | 27.84* | 78.5 | 0.2 | 28.305 | 79.79 | 0.21 | Goodwin and Deino, 1989 | Lower Kennedy Coulee, equivalent to Taber Coal Zone of Foremost Formation. Sanidine. *Original standard used was MMhb-1 = 520.4 +/- 1.7 Ma, which was equivalent to FCs = 27.84 (Renne et al., 1998). |
| Dinosaur Park | middle, 44 m above bottom | 27.84* | 75.2 | 0.3 | 28.305 | 76.45 | 0.31 | Eberth and Hamblin, 1993 | Sample from Dinosaur Provincial Park area. *The standard used is not mentioned in Eberth and Hamblin (1993), but the paper cites the methods of Thomas et al. (1990), which used the standard of MMhb-1 = 520.4 +/- 1.7 Ma, which was equivalent to FCs = 27.84 (Renne et al., 1998). |
| Oldman | upper, 4 m below top | 27.84* | 76.5 | 0.5 | 28.305 | 77.76 | 0.51 | Eberth and Hamblin, 1993 | Sample from Dinosaur Provincial Park area. *The standard used is not mentioned in Eberth and Hamblin (1993), but the paper cites the methods of Thomas et al. (1990), which used the standard of MMhb-1 = 520.4 +/- 1.7 Ma, which was equivalent to FCs = 27.84 (Renne et al., 1998). |
| Foremost | lower, 30 m above bottom | 27.84* | 79.14 | 0.15 | 28.305 | 80.45 | 0.16 | Eberth, 2005 citing A. L. Deino personal communication, 1993 | Sample from Dinosaur Provincial Park area. *The standard used is not mentioned in Eberth (2005), but in the early 1990s Deino’s lab, part of the Berkeley Geochronology Center, was using the Fish Canyon sanidine standard of 27.84 Ma (P. R. Renne personal communication, 2011). The samples listed above were tested in the same lab using the same standard. |
| Two Medicine | upper, 10 m below top | 27.84 | 74.08 | 0.05 | 28.305 | 75.30 | 0.07 | Rogers et al., 1993 | Sample TM-6 plagioclase. |
| Two Medicine | upper middle | 28.03 | 75.92 | 0.32 | 28.305 | 76.66 | 0.32 | Varricchio et al., 2010 | Bentonite is associated with the MOR TM-003 Maiasaura bonebed. |
| Two Medicine | lower, 100 m above bottom | 27.84 | 80.04 | 0.08 | 28.305 | 81.37 | 0.10 | Rogers et al., 1993 | Sample RT/TM-7 biotite. This original date was used to estimate age of ~79.43 Ma for MOR 1155, holotype of Acristavus gagslarsoni (Gates et al., 2011), which recalibrates to 80.74 Ma. |
| Wahweap | middle, 40 m above bottom | 28.02 | 80.1 | 0.3 | 28.305 | 80.91 | 0.31 | Jinnah et al., 2009 | Sample CF05-B bentonite sanidine. This original date was used to estimate age of 79.34–78.91 Ma for UMNHVP 16607, referred specimen of Acristavus gagslarsoni (Gates et al., 2011), which recalibrates to 80.14–79.71 Ma. |
Published dates have been recalibrated to the Fish Canyon sanidine standard (28.305 +/- 0.036 Ma) of Renne et al. [10]. Unless specified, stratigraphic heights "above bottom" and "below top" refer to the bottom and top of the entire formation, not its members. Ages and errors are in Ma. FCs: Fish Canyon sanidine standard used for published ages. MMhb-1: McClure Mountain hornblende standard. References used in Table 1: [11–15, 17–19].