View source for Earth:Yerrapalli Formation

{{Use Indian English|date=August 2019}}
{{Infobox rockunit
| name           = Yerrapalli Formation
| image          =
| caption        =
| type           = [[Earth:Geological formation|Geological formation]]
| period         = Anisian
| age            = Anisian<br>~{{fossil range|247|242}}
| prilithology   = Mudstone, [[Earth:Sandstone|sandstone]], [[Earth:Caliche|caliche]]
| otherlithology =
| namedfor       = Yerrapalli village
| namedby        = Jain ''et al.''
| year_ts        = 1964
| region         = Andhra Pradesh, Telangana
| country        = {{IND}}
| coordinates    = {{coord|18.9|N|79.7|E|display=inline,title}}
| paleocoordinates = {{coord|51.4|S|48.5|E|display=inline}}
| unitof         = 
| subunits       = 
| underlies      = Bhimaram Formation
| overlies       = Kamthi Formation
| thickness      = {{convert|600|m|ft|abbr=on}}
| extent         = Pranhita–Godavari Basin
| area           =
| map            = {{Location map+ | India#India Telangana
| relief = 1
| width   = 250
| float   = center
| places  =
  {{Location map~ | India#India Telangana
  | lat_deg = 18.9
  | lon_deg = 79.7
  | mark = Pink ff0080 pog.svg
  | marksize = 10
  }}
}}
| map_caption    =
}}

The '''Yerrapalli Formation''' is a [[Earth:Triassic|Triassic]] rock formation consisting primarily of mudstones that outcrops in the Pranhita–Godavari Basin in southeastern India.<ref name=SS70>{{Cite journal | last1 = Supriya Sengupta | doi = 10.1306/74D71F0A-2B21-11D7-8648000102C1865D | title = Gondwana Sedimentation Around Bheemaram (Bhimaram), Pranhita-Godavari Valley, India | journal = SEPM Journal of Sedimentary Research | year = 1970 | volume=40}}</ref> The Yerrapalli Formation preserves fossils of freshwater and terrestrial vertebrates as well as [[Biology:Trace fossil|trace fossil]]s of invertebrates.<ref name=FWYerrapalli>[http://www.fossilworks.org/cgi-bin/bridge.pl?action=displayStrata&geological_group=&formation=Yerrapalli&group_formation_member=Yerrapalli Yerrapalli Formation] at [[Biology:Fossilworks|Fossilworks]].org</ref> The [[Biology:Tetrapod|tetrapod]] fauna includes temnospondyl amphibians, archosauromorph reptiles, and dicynodonts.<ref name=SF10>{{cite book |last=Sues |first=H.-D. |author2=Fraser, N.C.  |year=2010 |chapter=Early and early Middle Triassic in Gondwana |title=Triassic Life on Land: The Great Transition |publisher=Columbia University Press |location=New York |isbn=9780231135221}}</ref>

== Geology ==
Most of the Yerrapalli Formation consists of red mudstones. The mudstones were deposited across a [[Earth:Floodplain|floodplain]] during the Anisian stage of the [[Earth:Middle Triassic|Middle Triassic]]. Smaller [[Earth:Lens (geology)|lenses]] of [[Earth:Calcareous|calcareous]] [[Earth:Sandstone|sandstone]] represent ephemeral streams that branched off from the larger channels that were the source of the floodplain sediments.<ref name=SF10/> The climate of the region during the time is thought to have been monsoonal with both wet and dry seasons.<ref name=BS88>{{Cite journal | last1 = Bandyopadhyay | first1 = S. | title = A Kannemeyeriid Dicynodont from the Middle Triassic Yerrapalli Formation | doi = 10.1098/rstb.1988.0072 | journal = Philosophical Transactions of the Royal Society B: Biological Sciences | volume = 320 | issue = 1198 | pages = 185–233| year = 1988 | bibcode = 1988RSPTB.320..185B | doi-access = free }}</ref>

The Yerrapalli Formation overlies the Kamthi Formation, underlies the Bhimaram Formation, and is [[Earth:Lithostratigraphy#Stratigraphic relationship|conformable]] with both formations. Two members of the Yerrapalli Formation have been recognized; a lower member consisting of layers of red and purple clay with lenses of pale green clay and an upper member consisting of alternating layers of clay and fine-grained sandstone.<ref name=BS88/>

== Paleobiota ==
The paleobiota of the Yerrapalli Formation is similar to that of the overlying Maleri Formation, which also preserves fossils of temnospondyls and archosauromorphs. The main difference between the Yerrapalli and the Maleri faunae is the presence of dicynodonts in the former. The discovery of dicynodont fossils in the Pranhita-Godavari Basin in 1964 was one of the earliest indications that the Yerrapalli Formation represented a distinct paleofauna. Before this discovery, Yerrapalli strata were grouped within the Maleri Formation.<ref name=BS88/> The dicynodonts of the Yerrapalli Formation are similar to those of the [[Earth:Ntawere Formation|Ntawere Formation]] in Zambia, which also dates back to the Anisian. During the Middle Triassic, what is now India and southern Africa formed one continuous landmass as part of the supercontinent [[Earth:Gondwana|Gondwana]].

=== Synapsids ===
{| class="wikitable sortable"
|-
! Taxon !! class="unsortable" | Material !! class="unsortable" | Notes !! class="unsortable" | Images
|-
| ''Rechnisaurus cristarhynchus''<ref name=CTR70>{{cite journal |last=Chowdhury |first=T.R. |year=1970 |title=Two new dicynodonts from the Triassic Yerrapalli Formation of central India |journal=Palaeontology |volume=13 |issue=1 |pages=132–144 |url=http://palaeontology.palass-pubs.org/pdf/Vol%2013/Pages%20132-144.pdf}}</ref>
 || A mostly complete skull || A kannemeyeriiform [[Biology:Dicynodont|dicynodont]] ||
|-
| <small>[[Biology:Trirachodontidae|Trirachodontidae]] indet.</small><ref name=JSL96/> || <small>Isolated teeth</small> || ||
|-
| ''Wadiasaurus indicus''<ref name=CTR70/> || || A kannemeyeriiform dicynodont || [[File:Wadiasaurus1DB.jpg|150px]]
|}

=== Reptiles ===
{| class="wikitable sortable"
|-
! Taxon !! class="unsortable" | Material !! class="unsortable" | Notes !! class="unsortable" | Images
|-
| ''Bharitalasuchus tapani'' <ref>{{Cite journal|last1=Ezcurra|first1=Martin D.|last2=Bandyopadhyay|first2=Saswati|last3=Gower|first3=David J.|title=A New Erythrosuchid Archosauriform from the Middle Triassic Yerrapalli Formation of South-Central India |journal=Ameghiniana |date=2021-04-30|url=https://www.ameghiniana.org.ar/index.php/ameghiniana/article/view/3416|language=en|volume=58|issue=2|pages=132–168–132–168|doi=10.5710/AMGH.18.01.2021.3416|s2cid=234217303 |issn=1851-8044}}</ref>|| || An erythrosuchid archosauriform ||
|-
| ''Mesodapedon kuttyi''<ref name=CS80>{{cite journal |last=Chatterjee |first=S. |year=1980 |title=The evolution of Rhyncosaurs |journal=Mémoires de la Société Géologique de France |volume=139 |pages=57–65}}</ref> || Two specimens including skull bones || A [[Biology:Rhynchosaur|rhynchosaur]] similar to ''Stenaulorhynchus stockleyi'' from the [[Earth:Manda Formation|Manda Formation]] of Tanzania, which is the same age as the Yerrapalli Formation ||
|-
| ''Pamelaria dolichotrachela''<ref name=SK03>{{Cite journal | last1 = Sen | first1 = K. | title = ''Pamelaria dolichotrachela'', a new prolacertid reptile from the Middle Triassic of India | doi = 10.1016/S1367-9120(02)00110-4 | journal = Journal of Asian Earth Sciences | volume = 21 | issue = 6 | pages = 663–681 | year = 2003 | bibcode = 2003JAESc..21..663S }}</ref> || One complete skeleton, one partial skeleton, and isolated bones || A long-necked [[Biology:Allokotosauria|allokotosauria]]n<ref name="Azendohsaurus15">{{Cite journal|last1=Nesbitt|first1=Sterling J.|last2=Flynn|first2=John J.|last3=Pritchard|first3=Adam C.|last4=Parrish|first4=J. Michael|last5=Ranivoharimanana|first5=Lovasoa|last6=Wyss|first6=André R.|date=2015-12-07|title=Postcranial Osteology of ''Azendohsaurus madagaskarensis'' (?Middle to Upper Triassic, Isalo Group, Madagascar) and its Systematic Position Among Stem Archosaur Reptiles|url=http://digitallibrary.amnh.org/dspace/bitstream/2246/6112/1/B398.pdf|journal=Bulletin of the American Museum of Natural History|language=en-US|volume=398|pages=1–126|doi=10.5531/sd.sp.15|issn=0003-0090|hdl=2246/6624|hdl-access=free}}</ref> archosauromorph || [[File:Pamelaria dolichotrachela.jpg|150px]]
|-
| ''Yarasuchus deccanensis''<ref name=SK05>{{Cite journal | last1 = Sen | first1 = K. | doi = 10.1111/j.1475-4983.2004.00438.x | title = A new rauisuchian archosaur from the Middle Triassic of India | journal = Palaeontology | volume = 48 | pages = 185–196 | year = 2005 | doi-access = free }}</ref> || An articulated, nearly complete skeleton and a partial disarticulated skeleton || A long-necked aphanosaurian [[Biology:Avemetatarsalia|avemetatarsalia]]n || [[File:Yarasuchus.jpg|150px]]
|}

=== Amphibians ===
{| class="wikitable sortable"
|-
! Taxon !! class="unsortable" | Material !! class="unsortable" | Notes !! class="unsortable" | Images
|- 
|style="background:#fbdddb;"| ''"Parotosuchus" rajareddyi'' || style="background:#fbdddb;"| || style="background:#fbdddb;"| A capitosaurid temnospondyl first referred to ''[[Biology:Parotosuchus|Parotosuchus]]'' but more recently considered either a species of ''[[Biology:Eryosuchus|Eryosuchus]]'' or of ''[[Biology:Stanocephalosaurus|Stanocephalosaurus]]''<ref name=SF10/> || style="background:#fbdddb;"|
|}

=== Fish ===
{| class="wikitable sortable"
|-
! Taxon !! class="unsortable" | Material !! class="unsortable" | Notes !! class="unsortable" | Images
|-
| ''Ceratodus'' sp.<ref name=JSL96>{{cite journal |last=Jain |first=S.L. |year=1996 |title=Aspects of vertebrate fossils from Pranhita-Godavari Valley with emphasis on dinosaur discoveries |journal=Journal of the Palaeontological Society of India |volume=41 |pages=1–16 |url=http://palaeontologicalsociety.in/vol41/v1.pdf}}</ref>
 || || A [[Biology:Lungfish|lungfish]] ||
|-
| [[Biology:Saurichthyidae|Saurichthyidae]] sp.<ref name=JSL96/> || ||  A chondrostean [[Biology:Ray-finned fish|ray-finned fish]] ||
|}

== See also ==
* [[Earth:Donguz Formation|Donguz Formation]], contemporaneous fossiliferous formation of Russia
* [[Earth:Ermaying Formation|Ermaying Formation]], contemporaneous fossiliferous formation of China
* [[Earth:Manda Formation|Manda Formation]], contemporaneous fossiliferous formation of Tanzania
* [[Earth:Ntawere Formation|Ntawere Formation]], contemporaneous fossiliferous formation of Zambia
* [[Earth:Omingonde Formation|Omingonde Formation]], contemporaneous fossiliferous formation of Namibia

== References ==
{{reflist}}

[[Category:Mudstone formations]]
[[Category:Fluvial deposits]]

{{Sourceattribution|Yerrapalli Formation}}