Near Ampandriambengy, around the area of Antsiranana: Turonian, Madagascar
collected by Farke & Sertich 2007
List of taxa
Where & when
Taphonomy & methods
Metadata & references
Reptilia - Abelisauridae
Dahalokely tokana n. gen., n. sp. Farke and Sertich 2013
|Holotype UA 9855, a partial axial column including cervical vertebra C?5, dorsal vertebrae D?1, D?2, and D?6–D?9, as well as a complete left dorsal rib (DR?2), capitula of two right dorsal ribs, proximal ends of two dorsal ribs, and other rib fragments|
|see common names|
|Coordinates:||13.8° South, 49.5° East (view map)|
|Paleocoordinates:||33.4° South, 40.4° East|
|Basis of coordinate:||estimated from map|
|Geographic resolution:||small collection|
|Stage:||Turonian||10 m.y. bin:||Cretaceous 6|
|Key time interval:||Turonian|
|Age range of interval:||93.90000 - 89.80000 m.y. ago|
|Stratigraphy comments: The middle, terrestrial unit of the "Ambolafotsy Formation", Turonian in age.
The section containing the Dahalokely site is informally termed the "Ambolafotsy Formation" and is divided into lower, middle (containing the type locality; Figure 1), and upper units . The lower unit has produced several biostratigraphically informative foraminifera, including Whiteinella aprica, W. baltica, Helvetoglobotruncana praehelvetica, and H. helvetica, and the nannofossil Quadrum gartneri [23,25], placing the sample within the Q. gartneri and H. helvetica zones . Relevant biostratigraphic zones and ranges were sourced from Ogg and Lugowski , which draws upon data from other published resources (particularly references within ), recalibrated to the Geologic Time Scale 2012 . Helvetoglobotruncana helvetica is the most informative of the foraminifera, defining a zone within the latter part of the early Turonian (,93.52–92.99 Ma). The earliest occurrence of Q. gartneri is during the second half of the early Turonian (93.55 Ma), and it persisted into the late Coniacian (,86.44 Ma). Thus, the co-occurrence of these two species suggests that the sediments of the lower unit were deposited during the latter part of the early Turonian (93.52–92.99 Ma). The upper unit contains the ammonite Subprionocyclus neptuni [23,24], a taxon restricted to the late Turonian (90.86–89.77 Ma). Because no biostratigraphically informative microfossils are known from the middle unit yet, these terrestrial deposits may have overlapped temporally with some of the marine biozones. Even so, this biostratigraphic evidence restricts the age of the type locality for Dahalokely to the interval including the latter part of the early Turonian through the late Turonian (93.52– 89.77 Ma).
Lithology and environment
|Primary lithology:||carbonaceous claystone|
|Secondary lithology:||"cross stratification" sandstone|
|Geology comments: The sediments of most of the middle unit of the Ambolafotsy Formation are interpreted as terrestrial, deposited during a marine regression . Carbonized plant fragments are quite common in the middle unit, along with claystones, shales, and cross-bedded sandstones. Marine microfossils and macrofossils are generally absent [23,25], although a deposit of ostreids several meters above the type locality for Dahalokely suggests that the area was deposited close to the shoreline.|
|Modes of preservation:||body|
|Size of fossils:||macrofossils|
Collection methods and comments
|Collection methods:||surface (in situ),field collection|
|Reason for describing collection:||taxonomic analysis|
|Collectors:||Farke & Sertich||Collection dates:||2007|
|Collection method comments: Permanent collection at the University of Antananarivo (UA; Antananarivo, Madagascar).
The specimen was discovered in situ in the field in northernmost Madagascar (Figure 1) during the 2007 field season.
All necessary permits were obtained for the described study, which complied with all relevant regulations. Fieldwork was conducted under permit from Ministe`re des Mines de Madagascar and in collaboration with the Ministere de l’Enseignement Supérieur et de la Recherche Scientifique de Madagascar.
|Authorizer:||R. Benson||Enterer:||R. Benson||Research group:||vertebrate|
|Created:||2013-04-19 17:14:56||Last modified:||2013-04-19 02:14:56|
|Access level:||the public||Released:||2013-04-19 17:14:56|
|Creative Commons license:||CC BY|
|46390.||A. A. Farke and J. J. W. Sertich. 2013. An abelisauroid theropod dinosaur from the Turonian of Madagascar. PLoS ONE 8(4):e62047 [R. Benson/R. Benson/R. Benson]|