The El Doctor Formation is a
geologic formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...
in
Mexico
Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
. It preserves
fossils
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
dating back to the
Albian
The Albian is both an age (geology), age of the geologic timescale and a stage (stratigraphy), stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early Cretaceous, Early/Lower Cretaceous epoch (geology), Epoch/s ...
and
Cenomanian
The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...
stages of the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
period.
[El Doctor Formation]
at Fossilworks
Fossilworks was a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world.
History
Fossilworks was cr ...
.org Ammonite
Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...
fossils show that age of Late Albian is more likely.
Description
The light grey micritic limestone sequence with intercalated black chert lenses was deposited in an open marine basin with a hypersaline and/or poorly oxygenated bottom.
[
]
Fossil content
The formation has provided the following fossils:[Feldmann et al., 2007]Rajiformes
Rajiformes is one of the four Order (biology), orders in the clade Batomorphi, often referred to as the superorder Batoidea, flattened cartilaginous fishes related to sharks. Rajiforms are distinguished by the presence of greatly enlarged pector ...
[Fielitz & González Rodríguez, 2010]
* '' Xeneichthys yanesi''
* '' Heckelichthys preopercularis''
* '' Motlayoichthys sergioi''
* '' Nunaneichthys mexicanus''
* '' Ichthyotringa mexicana''
* '' Muhichthys cordobai''
* '' Dalgoichthys tropicalis''
* '' Handuichthys interopercularis''
* '' Pseudomonocentris microspinosus''
* '' Araripichthys'' sp.
* '' Vinctifer'' sp.
* '' Pachyrhizodus'' sp.
* cf. '' Tselfatia''
* Pycnodontiformes
Pycnodontiformes is an extinct order of primarily marine bony fish. The group first appeared during the Late Triassic and disappeared during the Eocene. The group has been found in rock formations in Africa, Asia, Europe, North and South America. ...
* Cladocyclidae
* Elopiformes
* Gonorhynchiformes
* Mawsoniidae
Mawsoniidae is an extinct family of prehistoric coelacanth fishes which lived during the Triassic to Cretaceous periods. Members of the family are distinguished from their sister group, the Latimeriidae (which contains the living coelacanths of t ...
[Hegna et al., 2014]
* '' Victoriacaris muhiensis''[
* '' Palinurus sp.''
]
Ammonites
* '' Mortoniceras'' sp.
* ''Hamites'' aff. ''renzi''
* '' Beudanticeras'' sp.
Echinoderms
* Echinoidea
Sea urchins or urchins () are echinoderms in the class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal zone to deep seas of . They typically have a globular body covered by a spiny ...
* Crinoidea
Crinoids are marine invertebrates that make up the class Crinoidea. Crinoids that remain attached to the sea floor by a stalk in their adult form are commonly called sea lilies, while the unstalked forms, called feather stars or comatulids, are ...
See also
* List of fossiliferous stratigraphic units in Mexico
** Sierra Madre Formation
References
Bibliography
*
*
* {{citation , last1=Feldmann , first1=R. M. , first2=F. J. , last2=Vega , first3=L. , last3=Martínez López , first4=K. A. , last4=González Rodrigues , first5=O. , last5=González León , first6=M. , last6=Rosario Fernández-Barajas , year=2007 , title=Crustacea from the Muhi Quarry (Albian-Cenomanian), and a review of Aptian Mecochiridae (Astacidea) From Mexico , journal= Annals of Carnegie Museum , volume=76 , issue=3 , pages=145–156, doi=10.2992/0097-4463(2007)76 45:CFTMQA.0.CO;2
Geologic formations of Mexico
Cretaceous System of North America
Cretaceous Mexico
Albian Stage
Cenomanian Stage
Mudstone formations
Open marine deposits
Paleontology in Mexico