The Intertrappean Beds are a Late Cretaceous and early Paleogene geologic unit in India. These beds are found as interbeds between Deccan Traps layers, including the slightly older Lameta Formation. They consist a number of different subgroups and formations, and span the Cretaceous–Paleogene boundary.
Many mostly fragmentary fossils, especially of small vertebrates, are known from the formation. Indeterminate theropod and pterosaur remains have been recovered from the formation, as well as dinosaur eggs.Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607. The mammal genera Deccanolestes, Sahnitherium, Bharattherium, Indoclemensia, Indotriconodon and Kharmerungulatum have been recovered from several localities. The Early Eocene-aged Bamanbor locality in Gujarat preserves articulated freshwater fish specimens. A rich plant flora is known from the formation.
Stratigraphy Although often thought of as a contemporaneous unit that was formed in a single rapid eruption event, more studies that date the age of the volcanic beds indicate that the Deccan Traps did not erupt all at once. Instead, different portions appear to have erupted during different periods of time. This means that the Intertrappean Beds are best understood as a group of different volcanic-associate formations of varying ages.
Divisions Kale et al (2020) divided the group into the following provinces:
Sahyadri Group or Western Province (age: Late Maastrichtian to Danian, ~67.5 to 62.5 mya) Satpura Group or Central Province Malwa Group (age: Late Maastrichtian, ~67.7 mya; likely the oldest group) Amarkantak Group or Mandla Province (age: early Paleogene, ~64.5 mya - unknown)
Mittal et al (2021) divided the group into the following provinces:
Western Ghats-Central Indian Volcanic Province (WVP) (age: Late Maastrichtian to Danian) Saurhastra-Kutchh Province (age: ?Maastrichtian to early Eocene) Malwa Plateau Province (age: Late Maastrichtian) Mandla Lobe Province (age: early Paleogene)
Formations
Chemostratigraphic definition Kale et al (2020) divided the group as follows. Subgroups/formations are classified based on oldest to youngest.
Wai Subgroup (youngest) Desur Formation Panhala Formation Mahabaleshwar Formation (~63.2 mya) Ambenali Formation Poladpur Formation Lonavala Subgroup Bushe Formation Khandala Formation Kalsubai Subgroup (oldest, ~67.5 mya) Bhimashankar Formation Thakurwadi Formation Neral Formation Igatpuri Formation Jawhar Formation
Lithostratigraphic definition Kale et al (2020) divided the group as follows. Subgroups/formations are classified based on oldest to youngest.
Sahyadri Group: Bombay Subgroup (~62.5 mya) Borivali Formation Elephanta Formation Khandala Subgroup (~67.5 to 63.2 mya) Mahabaleshwar Formation (~63.2 mya) Purandargarh Formation Diveghat Formation Karla Formation Indrayani Formation Kalsubai Subgroup (oldest: ~67.5 mya) Upper Ratangarh Formation Lower Ratangarh Formation Salher Formation Satpura Group: Karanja Formation (youngest) Buldhana Formation Chikli Formation Ajanta Formation Upper Ratangarh Formation Karanja Formation Buldana Formation Chikli Formation (oldest) Malwa Group: Singarchori Formation (youngest) Bargonda Formation Indore Formation Kankaria-Pirukheri Formation Kalisindh Formation Mandleshwar Formation Gaganwara Formation (oldest) Amarkantak Group: Kuleru Formation (youngest) Khamla/Kampla Formation Amarwara Formation Multai Formation Linga Formation Pipardehi Formation Dhuma Formation Mandla Formation (oldest, ~64.4 mya) Within the newly defined Saurhastra Group (age: Paleocene to early Eocene), the following divisions were found by Patel & Shah (2023):
Ninama Basin: Ninama Limestone (youngest) Sukhbhadar Formation (oldest) Chotila Basin: Bamanbor Formation (youngest) Chotila Chert Rangpar Formation (oldest)
Paleobiota
Fish GenusSpeciesLocationStratigraphic positionMaterialNotesImagesAnthracopercaA. bhatiaiNaskal, RangapurOtolith.A percoid otolith.ApateodusA. striatusAsifabadAn enchodontoid aulopiform.Ariidaeincertae sedisNaskal, Rangapur, AnjarOtolith.An ariid catfish otolith.?BelonostomusB. indicusNagpurAn aspidorhynchid.CoupateziaC. spAsifabadAn eagle ray.Cyprinidaeincertae sedisDeothan-KheriA cyprinid.Dapalis D. ericiRangapurOtolith.A serranid otolith."Eotrigonodon""E." wardhaensisAsifabadInitially described as tetraodontiform, but likely represent grasping teeth of pycnodonts.EnchodusE. spAsifabadAn enchodontoid aulopiform.HoraclupeaH. intertrappeaBamanborEarly EoceneComplete skeleton.A clupeid.IgdabatisI. indicusKisalpuri & PiplanarayanwarAn eagle ray.IndiaichthysI. bamanborensisBamanborEarly EoceneMultiple complete skeletons.A possible percoid."Indotrigonodon""I." ovatusAsifabadInitially described as tetraodontiform, but likely represent grasping teeth of pycnodonts."Lepidotes""L." spAsifabadA lepisosteiform.LepisosteusL. indicusKisalpuri & PiplanarayanwarA gar.Nandidaeincertae sedisDeothan-KheriA nandid.Osteoglossidaeincertae sedisKisalpuri & PiplanarayanwarAn osteoglossid of uncertain affinities.PalaeolabrusP. dormaalensisAsifabadA palaeolabrid.PalaeopristolepisP. chiplonkariBamanborEarly EoceneMultiple partial skeletons.A questionable leaffish.P. feddeni"Perca""P." angustaBamanborEarly EoceneSkull.A possible percoid, classification very doubtful.Percomorphaincertae sedisBamanborEarly EocenePartial skeleton.A percomorph of uncertain affinities.PhareodusP. sp.Asifabad, Naskal & MarepalliA bonytongue.Polycanthidaeincertae sedisDeothan-KheriA polycanthid."Pisdurodon""P." spatulatusAsifabadInitially described as tetraodontiform, but likely represent grasping teeth of pycnodonts.Pycnodontidaeincertae sedisKisalpuri & PiplanarayanwarA pycnodontid of uncertain affinities."Pycnodus""P." lametaeAsifabadA pycnodontid.RajaR. sudhakariAsifabadA skate.RhombodusR. sp.AsifabadA stingray.Serranidaeincertae sedisDeothan-KheriA serranid.Siluriformesincertae sedisKisalpuri & PiplanarayanwarA catfish of uncertain affinities.Sphenodus S. sp.AsifabadA shark.StephanodusS. lybicusAsifabad & MarepalliA pycnodontid.
Otolith-based taxa GenusSpeciesLocationStratigraphic positionMaterialNotesImagesAmbassidarumA. cappettaiNagpurOtolithAn ambassid otolith.ApogonidarumA. curvatusNaskal, RangapurOtolithA cardinalfish otolith.BlenniidarumB. spRangapurOtolithA blenny otolith.?CentropomidarumC. takliensisNagpurOtolithA possible snook otolith.ClupeidarumC. valdiyaiNagpur, RangapurOtolithA clupeid otolith.C. sahniiGonorhynchidarumG. rectangulusNagpur, RangapurOtolithA gonorynchid otolith.HeterotidinarumH. heterotoidesNaskalOtolithAn arapaimine otolith.NotopteridarumN. nolfiNaskal, Rangapur, CheemalaguttaOtolithA notopterid otolith.OsteoglossidarumO. deccanensisNaskal, OtolithAn osteoglossid otolith.O. intertrappusPercoideorumP. citreumNaskal, Nagpur, RangapurOtolithPercoid otoliths.P. nagpurensisP. rangapurensis?PristolepidinarumP. jaegeriNagOtolithA possible pristolepid otolith.SerranidarumS. sp.AnjarOtolithA serranid otolith.
Amphibians GenusSpeciesLocationStratigraphic positionMaterialNotesImagesGobiatidaeincertae sedisNaskalA gobiatid frog."Hemisotidae"/"Leptodactylidae"incertae sedisNaskalA frog of uncertain affinities.IndobatrachusI. pusillusWorli HillEarly PaleoceneMultiple complete skeletonsA frog of uncertain affinities.Pelobatidaeincertae sedisNagpurA pelobatid frog.Ranoideaincertae sedisNaskalA ranoid frog.Costataincertae sedisA costatan frog?Caudataincertae sedisA possible salamander.
Reptiles
Turtles GenusSpeciesLocationStratigraphic positionMaterialNotesImagesCarteremysC. leithiiWorli HillEarly PaleoceneCarapace, plastron, skull and partial mandibleA turtle of uncertain affinities.SankuchemysS. sethnaiAmboli QuarrySkullA bothremydid turtle.
Lepidosaurs GenusSpeciesLocationStratigraphic positionMaterialNotesImagesAcrosphenodontiaIncertae sedisNaskalDentary with teeth.An indeterminate rhynchocephalian."Agama"A. sp.RangapurAn indeterminate agamid lizard.AnguidaeIncertae sedisNaskalAn indeterminate anguid lizard.?"Contogenys"?"C." sp.NagpurAn indeterminate scincomorph lizard.DeccansaurusD. palaeoindicusKesaviMaastrichtian/Early PaleoceneJaws & several osteoderms.A scincoid lizard.?"Exostinus""E." estestaiNagpurAn indeterminate xenosaurid lizard."Eumeces""E." sp.RangapurAn indeterminate scincid lizard.IndophisI. sahniiNaskalOver 160 vertebrae.A nigerophiid snake."Litakis""L." sp.NagpurAn indeterminate lizard."Pristiguana""P." sp.NagpurAn indeterminate iguanid lizard.SerpentesIncertae sedisNaskalA trunk vertebra & left dentary.A snake.SerpentesIncertae sedisPossibly a primitive form,MadtsoiidaeIncertae sedisThree individuals.Madsoid snakes.cf. Indophiscf. I. sahniiNigerophiidae snake.BooideaIncertae sedisPossibly a Booid snake.
Crocodyliforms GenusSpeciesLocationStratigraphic positionMaterialNotesImagesCrocodylidaeincertae sedisWorli HillTeeth and dentary.A crocodylid crocodyliform.Dyrosauridaeincertae sedisKisalpuriPartial mandible, frontal, and vertebraeA dyrosaurid crocodyliform.Crocodyliformesincertae sedisNaskalTeeth.Shows similarities to Hamadasuchus and perhaps Mahajangasuchus.
Dinosaurs GenusSpeciesLocationStratigraphic positionMaterialNotesImages?"Hypselosaurus""H." spMohgaon KalanA titanosaurian sauropod. Massospondylus M. rawesi Tooth Previously thought to be Massospondylus now thought to have been an indeterminate Theropod.SauropodaIncertae sedisAsifabad, Ranipur, AnjarBones. Anjar specimen consists of tibia, fibula, radius, ulna, femur, scapula, claws, ribs and vertebrae, remains are fragile but well-preserved.Ghevariya, Z. G. (1988). "Intertrappean Dinosaurian Fossils From Anjar Area, Kachchh District, Gujarat". Current Science. 57 (5): 148–151.Indeterminate sauropods.
Oogenera GenusSpeciesLocationStratigraphic positionMaterialNotesImagesMegaloolithusbaghensisKisalpuriEggshell fragmentsA Titanosaur egg.SubtiliolithuskachhensisKisalpuriEggshell fragmentsA Enantiornithine bird egg.
Pterosaurs GenusSpeciesLocationStratigraphic positionMaterialNotesImagesPterosauriaincertae sedisSirol-khal localityAn indeterminate dentulous pterosaur. May not be from the Maastrichtian.
Mammals GenusSpeciesLocationStratigraphic positionMaterialNotesImagesBharattheriumB. bonaparteiKisalpuriA fragmentary cheek-tooth.A sudamericid mammal.DeccanolestesD. hislopiNaskal microvertebrate siteMolars, calcanea, astralgi, humerus, ulna.A eutherian mammal.D. robustusNaskal microvertebrate site"Dental material and an astragalus".A eutherian mammal.D. narmadensisKisalpuri"Isolated rear molar."A eutherian mammal.Indoclemensia I. naskalensisNaskal microvertebrate siteRight second Molar.A eutherian mammal.I. magnusNaskal microvertebrate siteLeft second Molar.A eutherian mammal.IndotriconodonI. magnusKutchSingle lower Molar.A eutriconodont mammal.KharmerungulatumK. vanvaleniKisalpuriIsolated right lower molar.A eutherian mammal.SahnitheriumS. rangapurensisRangapur microvertebrate siteUpper Molar.A eutherian mammal.
Arthropods Genus Species Material Location Time Period Notes Images ?Buprestidae Indeterminate Maharashtra Maastrichtian A Jewel beetle. Lomatus L. hislopi Maharashtra Maastrichtian A Jewel beetle. ?Curculionidae Indeterminate Maharashtra Maastrichtian A Snout beetle. Meristos M. hunteri Maharashtra Maastrichtian A Snout beetle. Ostracoda Indeterminate Maharashtra Maastrichtian An Ostracod. Palaeotanymecides P. hislopi Maharashtra Maastrichtian A Snout beetle.
Mollusca