ABSTRACT This is the first detailed report of vertebrate tracks from alluvial plain deposits of t... more ABSTRACT This is the first detailed report of vertebrate tracks from alluvial plain deposits of the Boulder Creek Formation (Lower Cretaceous: middle to ?upper Albian) from outcrop exposures in northeastern British Columbia. Several in situ dinosaur tracks observed in vertical section are described, as well as the recovery and description of an isolated track slab discovered in the Boulder Gardens recreation area south of Tumbler Ridge, British Columbia. The vertebrate ichnites consist of three small tridactyl theropod dinosaur prints, one tetradactyl ornithopod print, and 72 small tridactyl tracks of avian affinity which are described as a new ichnotaxon herein. The avian prints are small (under 30 mm length) and are characterised by a large divarication between digits II and III and comparatively lesser divarication between digits III and IV. The pace and stride are short and the pace angulation is high. The tracks are similar to those produced by extant shorebirds and the track-maker likely occupied a similar niche. The avian prints are described herein as a new ichnotaxon, Paxavipes babcockensis ichnogen. et isp. nov. Two of the theropod footprints are identified as Irenichnites gracilis, an ichnotaxon described in 1932 by C.M. Sternberg from the Lower Cretaceous (Aptian) Gething Formation near Hudson's Hope, British Columbia. One of the Irenichnites gracilis prints displays skin impressions associated with the digital pads of digit III and the metatarsal pad. This is the first record of skin impressions from prints of Irenichnites gracilis. The ornithopod track is partial and unidentifiable to a particular ichnotaxon, but displays skin impressions on the metatarsal pad and at the base of the second digit impression. The skin impressions from the ornithopod track differ from the Irenichnites gracilis skin impressions.
The Kaskapau Formation is a mudstone-dominated wedge up to 950 m thick that spans late Cenomanian... more The Kaskapau Formation is a mudstone-dominated wedge up to 950 m thick that spans late Cenomanian to middle Turonian time. The formation has a prominent wedge geometry and was deposited in the foredeep of the Western Canada Foreland Basin. In outcrop in northeast British Columbia, nearshore sandstones are locally well developed and include rare wedges of nonmarine strata. On Quality Creek, near Tumbler Ridge, 11 m of nonmarine strata contain abundant dinosaur tracks and the first in situ dinosaur bone reported from British Columbia. This site, at a paleolatitude of about 67°N, preserves a rare glimpse of Turonian terrestrial environments during global eustatic highstand. Three main dinosaur habitats are recognized: strandplain and beach-ridge; freshwater lake; and brackish lagoon. Back-beach sandstone has a relief of about 2.5 m, interpreted as beach ridges; sandy coals containing abundant dinosaur tracks represent inter-ridge slough deposits. Overlying lake deposits comprising laminated muds with freshwater molluscs grade up into rooted muddy siltstone and locally, dinoturbated sandstone. Lake deposits are capped by lagoonal mudstone with abundant brackish-water molluscs, locally including a dinosaur-trampled oyster bioherm. The upper parts of sandy lagoonal deltas are pervasively dinoturbated. Sandstone filling a tidal channel contains logs, oyster shells, and bones of dinosaurs, turtles, and crocodiles, as well as fish scales. The lagoonal succession is erosively overlain by offshore sandy mudstones. Various lines of evidence suggest that the mean annual temperature at this sea-level location was about 14°C, with a cold-month mean no less than 5.5°C. The high-latitude location implies a significant period of winter darkness, and correspondingly diminished plant productivity.
Coniacian strata at Pueblo, Colorado, and coeval strata 1650 km to the NW at Horseshoe Dam, Alber... more Coniacian strata at Pueblo, Colorado, and coeval strata 1650 km to the NW at Horseshoe Dam, Alberta, has shown that physical disconformities, related to relative changes in sea level, can be recognized at each locality. Stratigraphic control provided by the succession of inoceramid bivalves suggests that at least two disconformities are synchronous, implying some degree of eustatic control on their formation. The new study shows that the Fort Hays Limestone Member of the Niobrara Formation, exposed near Pueblo, Colorado, contains a major faunal gap embracing the zones of Cremnoceramus waltersdorfensis hannovrensis and Cremnoceramus crassus inconstans; this faunal gap is also recognized over large areas of the U.S. western interior. The faunal gap was formerly explained in terms of biogeographic provincialism. However, study of an expanded proximal foredeep section of the Upper Turonian to Lower Coniacian Cardium Formation at Horseshoe Dam, in southern Alberta, revealed the presence of both C. waltersdorfensis hannovrensis and C. crassus inconstans zones. These zones are overlain, at Cardium transgressive surface E7, by strata with Cremnoceramus crassus crassus. Depositional successions and transgressive surfaces in the Horseshoe Dam section were traced, using wire-line logs, to coeval strata exposed at Deer Creek, Montana, 365 km to the SE. There, Cremnoceramus deformis erectus and Cremnoceramus waltersdorfensis waltersdorfensis occur above Cardium erosion surface E5.5 and mark the base of the Coniacian. The discovery of this succession of Lower Coniacian inoceramid faunas indicates that the North American rec ord can be directly interpreted in terms of the standard European zonation. At Pueblo, the stratigraphic gap corresponding to the missing C. waltersdorfensis hannovrensis and C. crassus inconstans zones is represented by a shell hash at the top of bed 37 of the Fort Hays Limestone; the top of this bed is correlated with the E7 surface at the top of the Cardium Formation. A second hiatus is recognized in the Fort Hays Limestone at a hardground at the top of bed 29; the inoceramid succession suggests that this surface correlates with a latest Turonian lowstand unconformity represented by the Cardium E5.5 surface in Alberta. The transgressiveregressive successions and their associated inoceramid faunas recorded by the E5.5 and E7 surfaces in Alberta, and equivalent surfaces in the Fort Hays Limestone in Colorado are comparable to the transgressive-regressive facies relationships and the inoceramid faunal succession documented in central Europe; this similarity implies an element of eustatic control on these relative sea-level changes.
ABSTRACT This is the first detailed report of vertebrate tracks from alluvial plain deposits of t... more ABSTRACT This is the first detailed report of vertebrate tracks from alluvial plain deposits of the Boulder Creek Formation (Lower Cretaceous: middle to ?upper Albian) from outcrop exposures in northeastern British Columbia. Several in situ dinosaur tracks observed in vertical section are described, as well as the recovery and description of an isolated track slab discovered in the Boulder Gardens recreation area south of Tumbler Ridge, British Columbia. The vertebrate ichnites consist of three small tridactyl theropod dinosaur prints, one tetradactyl ornithopod print, and 72 small tridactyl tracks of avian affinity which are described as a new ichnotaxon herein. The avian prints are small (under 30 mm length) and are characterised by a large divarication between digits II and III and comparatively lesser divarication between digits III and IV. The pace and stride are short and the pace angulation is high. The tracks are similar to those produced by extant shorebirds and the track-maker likely occupied a similar niche. The avian prints are described herein as a new ichnotaxon, Paxavipes babcockensis ichnogen. et isp. nov. Two of the theropod footprints are identified as Irenichnites gracilis, an ichnotaxon described in 1932 by C.M. Sternberg from the Lower Cretaceous (Aptian) Gething Formation near Hudson's Hope, British Columbia. One of the Irenichnites gracilis prints displays skin impressions associated with the digital pads of digit III and the metatarsal pad. This is the first record of skin impressions from prints of Irenichnites gracilis. The ornithopod track is partial and unidentifiable to a particular ichnotaxon, but displays skin impressions on the metatarsal pad and at the base of the second digit impression. The skin impressions from the ornithopod track differ from the Irenichnites gracilis skin impressions.
The Kaskapau Formation is a mudstone-dominated wedge up to 950 m thick that spans late Cenomanian... more The Kaskapau Formation is a mudstone-dominated wedge up to 950 m thick that spans late Cenomanian to middle Turonian time. The formation has a prominent wedge geometry and was deposited in the foredeep of the Western Canada Foreland Basin. In outcrop in northeast British Columbia, nearshore sandstones are locally well developed and include rare wedges of nonmarine strata. On Quality Creek, near Tumbler Ridge, 11 m of nonmarine strata contain abundant dinosaur tracks and the first in situ dinosaur bone reported from British Columbia. This site, at a paleolatitude of about 67°N, preserves a rare glimpse of Turonian terrestrial environments during global eustatic highstand. Three main dinosaur habitats are recognized: strandplain and beach-ridge; freshwater lake; and brackish lagoon. Back-beach sandstone has a relief of about 2.5 m, interpreted as beach ridges; sandy coals containing abundant dinosaur tracks represent inter-ridge slough deposits. Overlying lake deposits comprising laminated muds with freshwater molluscs grade up into rooted muddy siltstone and locally, dinoturbated sandstone. Lake deposits are capped by lagoonal mudstone with abundant brackish-water molluscs, locally including a dinosaur-trampled oyster bioherm. The upper parts of sandy lagoonal deltas are pervasively dinoturbated. Sandstone filling a tidal channel contains logs, oyster shells, and bones of dinosaurs, turtles, and crocodiles, as well as fish scales. The lagoonal succession is erosively overlain by offshore sandy mudstones. Various lines of evidence suggest that the mean annual temperature at this sea-level location was about 14°C, with a cold-month mean no less than 5.5°C. The high-latitude location implies a significant period of winter darkness, and correspondingly diminished plant productivity.
Coniacian strata at Pueblo, Colorado, and coeval strata 1650 km to the NW at Horseshoe Dam, Alber... more Coniacian strata at Pueblo, Colorado, and coeval strata 1650 km to the NW at Horseshoe Dam, Alberta, has shown that physical disconformities, related to relative changes in sea level, can be recognized at each locality. Stratigraphic control provided by the succession of inoceramid bivalves suggests that at least two disconformities are synchronous, implying some degree of eustatic control on their formation. The new study shows that the Fort Hays Limestone Member of the Niobrara Formation, exposed near Pueblo, Colorado, contains a major faunal gap embracing the zones of Cremnoceramus waltersdorfensis hannovrensis and Cremnoceramus crassus inconstans; this faunal gap is also recognized over large areas of the U.S. western interior. The faunal gap was formerly explained in terms of biogeographic provincialism. However, study of an expanded proximal foredeep section of the Upper Turonian to Lower Coniacian Cardium Formation at Horseshoe Dam, in southern Alberta, revealed the presence of both C. waltersdorfensis hannovrensis and C. crassus inconstans zones. These zones are overlain, at Cardium transgressive surface E7, by strata with Cremnoceramus crassus crassus. Depositional successions and transgressive surfaces in the Horseshoe Dam section were traced, using wire-line logs, to coeval strata exposed at Deer Creek, Montana, 365 km to the SE. There, Cremnoceramus deformis erectus and Cremnoceramus waltersdorfensis waltersdorfensis occur above Cardium erosion surface E5.5 and mark the base of the Coniacian. The discovery of this succession of Lower Coniacian inoceramid faunas indicates that the North American rec ord can be directly interpreted in terms of the standard European zonation. At Pueblo, the stratigraphic gap corresponding to the missing C. waltersdorfensis hannovrensis and C. crassus inconstans zones is represented by a shell hash at the top of bed 37 of the Fort Hays Limestone; the top of this bed is correlated with the E7 surface at the top of the Cardium Formation. A second hiatus is recognized in the Fort Hays Limestone at a hardground at the top of bed 29; the inoceramid succession suggests that this surface correlates with a latest Turonian lowstand unconformity represented by the Cardium E5.5 surface in Alberta. The transgressiveregressive successions and their associated inoceramid faunas recorded by the E5.5 and E7 surfaces in Alberta, and equivalent surfaces in the Fort Hays Limestone in Colorado are comparable to the transgressive-regressive facies relationships and the inoceramid faunal succession documented in central Europe; this similarity implies an element of eustatic control on these relative sea-level changes.
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