Portland Formation
Portland Formation | |
---|---|
Stratigraphic range: Hettangian-Sinemurian ~199–195 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓ | |
Type | Geological formation |
Unit of | Agawam Group, Newark Supergroup |
Sub-units | Turners Falls Sandstone & Mount Toby Formation |
Overlies | East Berlin Formation |
Lithology | |
Primary | Sandstone |
Other | Mudstone, siltstone, limestone |
Location | |
Coordinates | ![]() ![]() Portland Formation (the United States) Show map of the United States![]() ![]() Portland Formation (Massachusetts) Show map of Massachusetts |
The Portland Formation is a geological formation in Connecticut and Massachusetts in the northeastern United States.[1] It dates back to the Early Jurassic period.[2] The formation consists mainly of sandstone laid down by a series of lakes (in the older half of the formation) and the floodplain of a river (in the younger half). The sedimentary rock layers representing the entire Portland Formation are over 4 kilometres (2.5 mi) thick and were formed over about 4 million years of time, from the Hettangian age (lower half) to the late Hettangian and Sinemurian ages (upper half).[3]
In 2016, the paleontologist Robert E. Weems and colleagues suggested the Portland Formation should be elevated to a geological group within the Newark Supergroup (as the Portland Group), and thereby replacing the former name "Agawam Group". They also reinstated the Longmeadow Sandstone as a formation (within the uppermost Portland Group); it had earlier been considered identical to the Portland Formation.[4]
Vertebrate paleofauna
Dinosaur coprolites are known from the formation.[2] This formation and the underlying East Berlin Formation are well-known for its numerous well-preserved dinosaur tracks, which represent ornithischians, theropods, and sauropodomorphs, which are preserved at sites such as Dinosaur Footprints Reservation.[2][5] Other tracks are also known representing animals such as pseudosuchians, turtles, and temnospondyls.[6]
Dinosaurs | ||||||
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Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Anchisaurus[2] | A. polyzelus[2] |
| ![]() | |||
Podokesaurus[2] | P. holyokensis | Massachusetts | Partial postcranial skeleton.[7] | All known remains of this species have been destroyed.[citation needed] | ![]() | |
Neotheropoda sp.[8] | Massachusetts | Partial humerus. | Estimated to have been 9 meters long, and possibly a semiaquatic piscivore. |
Non-Dinosaur Archosaurs | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Stegomosuchus[9] | S. longipes | Hine's Quarry, Longmeadow | Partial postcranial skeleton. | Originally Stegomus. A small armored "protosuchian" crocodyliform. | ![]() | |
Pterosauria sp.[10] | South Hadley, Massachusetts | Partial Wrist and tooth. | Non-pterodactyloid pterosaur estimated to have a wingspan of 40 cm. |
Fish | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Redfieldius[11] | R. gracilis | The last surviving redfieldiiform fish. | ![]() | |||
Semionotus[11] | S. sp. | A semionotid fish. | ![]() |
Invertebrate paleofauna
Insects | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Holcoptera | H. schlotheimi[12] | A coptoclavid beetle. | ![]() | |||
H. giebeli[13] | ||||||
Orthoptera sp.[13] | An indeterminate orthopteran | |||||
Blattaria sp.[13] | An indeterminate cockroach |
See also
References
- ^ Portland Formation - USGS
- ^ a b c d e f g h Weishampel et al., 2004, pp.530–532
- ^ Olsen, P.E. (2002). "Stratigraphy and Age of the Early Jurassic Portland Formation of Connecticut and Massachusetts: A Contribution to the Time Scale of the Early Jurassic". Geological Society of America (Abstract). Archived from the original on 2018-11-28. Retrieved 2017-07-07.
- ^ Weems, R. E.; Tanner, L. H.; Lucas, S. G. (2016). "Synthesis and revision of the lithostratigraphic groups and formations in the Upper Permian?–Lower Jurassic Newark Supergroup of eastern North America". Stratigraphy. 13 (2): 111–153. doi:10.29041/strat.13.2.03.
- ^ Getty, Patrick (2004). "Ornithischian ichnites from Dinosaur Footprint Reservation (Early Jurassic Portland Formation), Holyoke, MA". Journal of Vertebrate Paleontology. 23 (Supp 3): 63A. doi:10.1080/02724634.2003.10010538. S2CID 220410105.
- ^ "PBDB". paleobiodb.org. Retrieved 2024-02-09.
- ^ "Table 3.1," in Weishampel et al., 2004, p.48
- ^ McMenamin, M. (2021). Large neotheropod from the Lower Jurassic of Massachusetts. AcademiaLetters, Article 3591. doi:10.20935/AL3591.1©2021 by the author — Open Access — Distributed under CC BY 4.0
- ^ von Huene, Friedrich (1922). "The Triassic reptilian order Thecodontia". American Journal of Science. 4 (19): 22–26. Bibcode:1922AmJS....4...22H. doi:10.2475/ajs.s5-4.19.22.
- ^ https://www.researchgate.net/publication/355340350_Early_Jurassic_pterosaur_from_Massachusetts [bare URL]
- ^ a b "PBDB". paleobiodb.org. Retrieved 2024-02-09.
- ^ "PBDB". paleobiodb.org. Retrieved 2024-02-09.
- ^ a b c "PBDB". paleobiodb.org. Retrieved 2024-02-09.
Bibliography
- Weishampel, David B.; Dodson, Peter; Osmólska, Halszka, eds. (2004). The Dinosauria, 2nd edition. Berkeley: University of California Press. ISBN 0-520-24209-2. Retrieved 2019-02-21.