# Time range of Hexanchiformes species

The shark order Hexanchiformes (in a broad sense, not only comprising the cow sharks, but also including the frilled sharks, Chlamydoselachidae) is often considered the most primitive of extant sharks, since they share some features with Paleozoic and early-Mesozoic shark groups as the Cladoselachiformes. Thus, it is interesting to see how far back the fossil record of this order reaches.

## Family Chlamydoselachidae

| Species | Lower Cretaceous | Lower Cretaceous | Lower Cretaceous | Lower Cretaceous | Lower Cretaceous | Lower Cretaceous | Upper Cretaceous | Upper Cretaceous | Upper Cretaceous | Upper Cretaceous | Upper Cretaceous | Upper Cretaceous | Paleocene | Paleocene | Paleocene | Eocene | Eocene | Eocene | Eocene | Oligocene | Oligocene | Miocene | Miocene | Miocene | Miocene | Miocene | Miocene | Pliocene | Pliocene | Pliocene | Pleistocene | Pleistocene | Pleistocene | Holocene | Extant |
| Species | B | V | H | B | A | A | C | T | C | S | C | M | D | S | T | Y | L | B | P | R | C | A | B | L | S | T | M | Z | P | G | L | M | U | Holocene | Extant |
| Chlamydoselachus thomsoni | | | | | | | | | | | |
| Chlamydoselachus gracilis | | | | | | | | | | | | |
| Chlamydoselachus goliath | | | | | | | | | | | | |
| Proteothrinax baumgartneri | | | | | | | | | | | | | | | | | |
| Chlamydoselachus fiedleri | | | | | | | | | | | | | | | | | | |
| Chlamydoselachus tobleri | | | | | | | | | | | | | | | | | | | | . | . | | | | | | |
| Chlamydoselachus bracheri | | | | | | | | | | | | | | | | | | | | | | | |
| Chlamydoselachus lawleyi | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| Chlamydoselachus anguineus | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |

## Family Hexanchidae

| Species | Lower Cretaceous | Lower Cretaceous | Lower Cretaceous | Lower Cretaceous | Lower Cretaceous | Lower Cretaceous | Upper Cretaceous | Upper Cretaceous | Upper Cretaceous | Upper Cretaceous | Upper Cretaceous | Upper Cretaceous | Paleocene | Paleocene | Paleocene | Eocene | Eocene | Eocene | Eocene | Oligocene | Oligocene | Miocene | Miocene | Miocene | Miocene | Miocene | Miocene | Pliocene | Pliocene | Pliocene | Pleistocene | Pleistocene | Pleistocene | Holocene | Extant |
| Species | B | V | H | B | A | A | C | T | C | S | C | M | D | S | T | Y | L | B | P | R | C | A | B | L | S | T | M | Z | P | G | L | M | U | Holocene | Extant |
| Heptranchias howellii | | | | | | | | | | | | . | |
| Heptranchias ezoensis | | | | | | | | | | | | | | | | | | | | | |
| Heptranchias tenuidens | | | | | | | | | | | | | | | | | | | | | |
| Heptranchias perlo | | | | | | | | | | | | | | | | | | | | | | | | | | | . | . | - | - | - | - | - | - | |
| Genus | Species | Early Jurassic | Early Jurassic | Early Jurassic | Early Jurassic | Middle Jurassic | Middle Jurassic | Middle Jurassic | Middle Jurassic | Upper Jurassic | Upper Jurassic | Upper Jurassic | Lower Cretaceous | Lower Cretaceous | Lower Cretaceous | Lower Cretaceous | Lower Cretaceous | Lower Cretaceous | Upper Cretaceous | Upper Cretaceous | Upper Cretaceous | Upper Cretaceous | Upper Cretaceous | Upper Cretaceous | Paleocene | Paleocene | Paleocene | Eocene | Eocene | Eocene | Eocene | Oligocene | Oligocene | Miocene | Miocene | Miocene | Miocene | Miocene | Miocene | Pliocene | Pliocene | Pliocene | Pleistocene | Pleistocene | Pleistocene | Holocene | Extant |
| Genus | Species | H | S | P | T | A | B | B | C | O | K | T | B | V | H | B | A | A | C | T | C | S | C | M | D | S | T | Y | L | B | P | R | C | A | B | L | S | T | M | Z | P | G | L | M | U | Holocene | Extant |
| Hexanchus | arzoensis | | | | |
| | microdon “agassizii” | | | | | | | | | | | | | | | | | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . | . |
| | gracilis | | | | | | | | | | | | | | | | | | | | | | |
| | collinsonae | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| | hookeri | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| | agassizi | | | | | | | | | | | | | | | | | | | | | | | | | | | . | . | . | . | | |
| | griseus | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | . | . | - | - | - | - | - | - | - | - | - | - | - | - | - | |
| | nakamurai “vitulus” | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| | griseus “andersoni” “gigas" | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | . | . | . | . | . | . | | | |
| Notidanoides | - | | | | | | | | | | . | - | - | - | - | - | - | - | - | - | - | - | |
| Notidanodon | lanceolatus | | | | | | | | | | | | | | . | . | - | |
| | antarcti | | | | | | | | | | | | | | | | | | | | | | |
| | dentatus | | | | | | | | | | | | | | | | | | | | | | |
| | pectinatus | | | | | | | | | | | | | | | | | | | | | | |
| | brotzeni” | | | | | | | | | | | | | | | | | | | | | | | | | |
| | loozi” | | | | | | | | | | | | | | | | | | | | | | | | | |
| Notorynchus | “Notidanus” aptiensis” | | | | | | | | | | | | | | | | | | | | |
| | “Notidanus” intermedius | | | | | | | | | | | |
| | “Notidanus” lawleyi | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| | “Notidanus” munsteri | | | | | | | | | | | |
| | “Notidanus” cepedianus “primigenius” “kempi” | | | | | | | | | | | | | | | | | | | | | | | | | | | | . | . | . | . | . | . | . | . | . | . | . | | | |
| | “Notidanus” serratissimus | | |
| | “Notidanus” serratus | | |