Calvert Formation
Geologic formation in the United States
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The Calvert Formation is a geologic formation in Maryland, Virginia, and Delaware. It preserves fossils dating back to the early to middle Miocene epoch of the Neogene period, between 23 and 14 million years ago.[1] It is one of the three formations which make up the Calvert Cliffs, all of which are part of the Chesapeake Group.
| Calvert Formation | |
|---|---|
| Stratigraphic range: | |
Outcrops of the Calvert Formation at the Calvert Cliffs State Park | |
| Type | Formation |
| Unit of | Chesapeake Group |
| Underlies | Choptank Formation |
| Overlies | Old Church Formation |
| Location | |
| Region | Maryland, Virginia, Delaware |
| Country | United States |
| Type section | |
| Named for | Calvert County |
Fossils
The Calvert Formation is extremely fossiliferous, although the most fossiliferous layers constitute a relative small section of it, dating to about 16 to 14.5 million years ago. Sediments under these layers are composed of either fine sand with few shells or (for the earliest layers) diatomite.[1] Some of the fossil species represented include the following:[2][3]
Chondrichthyes
Holocephalians
| Genus | Species | Family | Location | Stratigraphic Position | Material | Notes | Images |
|---|---|---|---|---|---|---|---|
| Edaphodon | Edaphodon sp. | Callorhynchidae | two well preserved mandibular plates | Similar to E. sweeti | |||
| Ischyodus | Ischyodus sp. | Callorhynchidae | many tooth fragments occasional mandibular plates | ||||
| Chimaera | Chimaera sp. | Chimaeridae |
Elasmobranchii
| Genus | Species | Location | Family | Stratigraphic Position | Material | Notes | Images |
|---|---|---|---|---|---|---|---|
| Notorynchus | N. primigenius | Hexanchidae | Similar to extant N. cepedianus but differs in distribution. | ||||
| Hexanchus | H. gigas | Hexanchidae | Far less common then N. primigenus | ||||
| Echinorhinus | E. blakei | Echinorhinidae | Teeth and bramble thorns | One of the rarest sharks in the cliffs, prefers deeper waters | |||
| Squalus | Squalus sp. 1
Squalus sp. 2 |
Squalidae | Very rare | Two forms of teeth, one (S. sp. 2) similar to Squalus acanthias | |||
| Squatina | Squatina sp. | Squatinidae | Teeth and Dermal thorns | ||||
| Rhincodon | R. typus | Rhincodontidae | Very similar to modern R. typus |  | |||
| Carcharias | C. cuspidatus
C. taurus C. reticulatus |
Odontaspididae | |||||
| Carcharoides | C. catticus | Lamnidae | |||||
| Isurus | I. oxyrinchus
I. retroflexus |
Lamnidae |  | ||||
| Carcharodon | C. hastalis
C. subserratus |
Lamnidae | presence of C. carcharias | ||||
| Otodus | O. chubutensis | Otodontidae | |||||
| Parotodus | P. benedenii | incertae sedis | |||||
| Alopias | A. cf. vulpinus | Alopiidae | A second large species of Alopias is known from teeth with larger and coarser serrated cutting edges then A. grandis | ||||
| Cetorhinus | Cetorhinus sp. | Cetorhinidae | |||||
| Scyliorhinidae sp. | Scyliorhinidae | ||||||
| Mustelus | Mustelus sp. |
- Physogaleus contortus
- Physogaleus hemmooriensis
- Galeocerdo aduncus
- Carcharhinus egertoni
- Hemipristis serra
- Carcharoides catticus
- Negaprion brevirostris
- Rhizoprionodon
- Sphryna laevissima
Rays and other cartilaginous fish
- Mobula pectinata
- Mobula fragilis
- Mobula loupianensis
- Plinthicus stenodon
- Rhinoptera cf. R. studeri
- Aetobatus arcuatus
- Pteromylaeus sp.
- Dasyatis probsti
- Dasyatis rugosa
- Pristis sp.
Bony fish
- Acipenseridae indet.
- Bagre sp.
- Brotula sp.
- Pogonias sp.
- Sciaenops sp.
- Tautoga sp.
- Acanthocybium cf. solandri
- Thunnus sp.
- Istiophorus cf. platypterus
- Ranzania grahami
- Ranzania tenneyorum
- Ariopsis stauroforus
- Trisopterus sculptus
- Micromesistius cognatus
- Prionotus
- Lophius sp.
- Paralbula dorisiae
- Morone
- Lophokatilus ereboorensis
- Rachycentron sp.
- Pomatomus sp.
- Lagodon sp.
- Micropogonias sp.
- Sphyraena sp.
- Sarda sp.
- Makaira cf. nigricans
- Chilomycterus sp.
Cetaceans
- Atlanticetus patulus
- Squalodon calvertensis
- Eurhinodelphis sp.
- Parietobalaena palmeri
- Eobalaenoptera harrisoni
- Cephalotrophis coronatus
- Araeodelphis
- Cetotherium
- Zarhachis flagellator
- Pelocetus
- Xiphiacetus
Pinnipeds
Crocodilians
- Thecachampsa antiquus
- Thecachampsa sericodon
Invertebrates
- Chesapecten nefrens
- Chesapecten coccymelus
- Isognomon sp.
- Ecphora
- Architectonica trilineata
Terrestrial mammals
- Cynarctus marylandica
- Tomarctus brevirostris
- Gomphotherium calvertensis
- Hipparion cf. phosphorum
- Amphicyon cf. frendens
- Amphicyon intermedius
- Aphelops sp.
- Archaeohippus cf. blackbergi
Birds
- Mergus miscellus
- Morus loxostylus
- Calonectris kurodai
- Heliadornis ashbyi
- Miocepphus
- Pelagornis
