Modelo Formation

Modelo Formation
Stratigraphic range: Late Miocene, 13–5.5 Ma
TypeFormation
Unit ofLos Angeles Basin
UnderliesPico Formation
OverliesRincon Shale
Thickness600 metres (2,000 ft)
Lithology
PrimaryShale
Location
RegionLos Angeles County and Ventura County, California
CountryUnited States
ExtentSimi Hills, Santa Susana Mountains

The Modelo Formation is a Miocene geologic formation in the Simi Hills and western Santa Susana Mountains of southern California, including under parts of Los Angeles.

It preserves fossils dating back to the Late Miocene of the Neogene period, among them a high number of fossil representatives of modern pelagic and deep-sea fish taxa (as well as some with benthic affinities), in addition to some seabirds and cetaceans. As suggested from this fauna, the sediments of the formation were likely deposited in a deepwater marine habitat at middle to upper bathyal depths within an abyssal fan, with geological changes along the San Andreas fault causing a rapid uplift during the latest Miocene, bringing these former deepwater sediments to the surface.[1] It is likely partially contemporaneous with the Monterey Formation in some areas, such as the Ventura Basin.[2]

Volcanic ash beds are known from the formation; these, along with fossil microorganisms, indicate that the formation was deposited between 13 and 5.5 million years ago.[3]

Paleobiota

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Based on the Paleobiology Database and Fierstine et al (2012). Much of the fauna is shared with the Monterey Formation, though some distinct taxa are also known:[4][5]

Bony fish

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Based on Fierstine et al (2012). Many of these taxa were described by David Starr Jordan from specimens excavated during the construction of the Sepulveda Boulevard Tunnel through the Santa Monica Mountains.[5]

Genus Species Location Member Material Notes Images
Absalomichthys A. velifer Articulated skeletons A manefish.
Araeosteus A. rothi Articulated skeletons A relative of the prowfish.
Argyropelecus A. bullockii Articulated skeletons A marine hatchetfish.
Bathylagus B. angelensis Articulated skeletons A deep-sea smelt.
Bolinichthys B. sp. Articulated skeletons A lanternfish.[6]
Chalcidichthys C. malacopterygius Articulated skeletons A manefish.
Chauliodus C. eximius Articulated skeletons A viperfish.
?Clupea ?C. tiejei Articulated skeleton A herring, classification in Clupea uncertain.
Cyclothone C. solitudinis Lower Articulated skeleton A bristlemouth.
Decapterus D. hopkinsi Articulated skeleton A mackerel scad.
D. sp.
Diaphus D. bolini Articulated skeletons A lanternfish.
Eclipes E. santamonicae Articulated skeletons A cod.
E. veternus
Etringus E. scintillans Articulated skeletons, isolated scales A herring, possibly a round herring.
Ganolytes G. aratus Articulated skeletons, isolated scales A herring.
G. cameo
Hipposyngnathus H. imporcitor Upper Articulated skeletons A pipefish.
Plectrites P. classeni Articulated skeletons A seabream.
Quaesita Q. quisquilia Articulated skeletons A deep-sea smelt.
Lampanyctus L. petrolifer Articulated skeletons A lanternfish, L. petrolifer potentially in an undescribed genus.
L. sp.
Laytonia L. californica Articulated skeleton A halosaur.
Lompoquia L. culveri Articulated skeleton A drumfish.
L. retropes
L. sp.
Molidae indet. An ocean sunfish.
Myctophum M. sp. Articulated skeletons A lanternfish.[6]
Pseudoseriola P. gilliandi Articulated skeletons A relative of the bluefish.
P. sp.
Rhomurus R. fulcratus Partial skeleton A halfbeak, either in the Hemiramphidae or the extinct Forficidae.
Sarda S. stockii Partial skeletons A bonito.
Scomber S. sanctaemonicae Partial skeleton A true mackerel.
S. cf. japonicus (=Pneumatophorus cf. grex) Scale
S. sp. Mulholland Drive Partial skeletons
Scomberesox S. edwardsi Lower Skull, partial segment with scales A saury.
Scorpaena S. ensiger Articulated skeletons A scorpionfish.
Sebastes S. davidi Articulated skeletons A rockfish.
S. sp.
Syngnathus S. avus Articulated skeletons A pipefish.
Thyrsocles T. kriegeri Articulated skeletons A euzaphlegid.
Xyne X. grex Articulated skeletons, isolated scales A herring.
Zanteclites Z. sp. Isolated scales A Neotropical silverside.
Zaphlegulus Z. venturaensis A euzaphlegid.

Birds

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Based on the Paleobiology Database:[4]

Genus Species Location Member Material Notes Images
Osteodontornis O. orri Sherman Oaks A pseudotooth bird.
Phalacrocorax P. femoralis A cormorant.
Puffinus P. diatomicus Sherman Oaks Incomplete skeleton. A shearwater.
Sula S. willetti Sherman Oaks Leg bones. A booby.

Mammals

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Based on the Paleobiology Database:[4]

Genus Species Location Member Material Notes Images
Atocetus A. nasalis Upper A kentriodontid toothed whale.
Mixocetus M. elysius Lincoln Heights Elysian Park Sandstone Skull A tranatocetid baleen whale, for which the formation is the type locality.

See also

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References

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  1. ^ Rumelhart, Peter E.; Ingersoll, Raymond V. (1997). "Provenance of the upper Miocene Modelo Formation and subsidence analysis of the Los Angeles basin, southern California: Implications for paleotectonic and paleogeographic reconstructions". Geological Society of America Bulletin. 109 (7): 885–899. doi:10.1130/0016-7606(1997)109<0885:POTUMM>2.3.CO;2.
  2. ^ Gilbert, J. Clark; Jobe, Zane R. (2023-08-29). "Submarine-Channel Element Architecture Demonstrates Facies Heterogeneity in Both Strike and Dip Views: Miocene Modelo Formation, Lake Piru, California, USA". The Sedimentary Record. 21 (1). doi:10.2110/001c.84246.
  3. ^ Knott, Jeffrey R.; Sarna-Wojcicki, Andrei M.; Barron, John A.; Wan, Elmira; Heizler, Lynn; Martinez, Priscilla (2022-09-26), Aiello, Ivano W.; Barron, John A.; Ravelo, A. Christina (eds.), "Tephrochronology of the Miocene Monterey and Modelo Formations, California", Understanding the Monterey Formation and Similar Biosiliceous Units across Space and Time, Geological Society of America, pp. 187–214, doi:10.1130/2022.2556(08), ISBN 978-0-8137-2556-7, retrieved 2024-09-23
  4. ^ a b c Czaplewski, John J. "PBDB Navigator". Paleobiology Database. Retrieved 2024-09-23.
  5. ^ a b California Academy of Sciences (1890). Occasional papers of the California Academy of Sciences. California Academy of Sciences. San Francisco : California Academy of Sciences.
  6. ^ a b Denton, John S. S. (2013). "Lanternfish (Teleostei, Myctophiformes, Myctophidae) body fossils from the Modelo Formation (upper Miocene) of Los Angeles County, California". Journal of Vertebrate Paleontology. 33 (4): 786–793. doi:10.1080/02724634.2013.751919. ISSN 0272-4634.