Doug Perrine / Sixgill or Cow shark (Hexanchus griseus) tooth row from lower jaw on display at Oceanographic Museum of Monaco, Principality of Monaco (digitally modified)

Doug Perrine / Sandbar shark (Carcharhinus plumbeus) 2.08m specimen, lower jaw with teeth on display at Oceanographic Museum of Monaco, Principality of Monaco (digitally modified)

Doug Perrine / Sandbar shark (Carcharhinus plumbeus) 2.08m specimen, upper jaw with teeth on display at Oceanographic Museum of Monaco, Principality of Monaco (digitally modified)

Claudio Contreras / American crocodile (Crocodylus acutus) extreme close up of animal resting on seagrass, Banco Chinchorro Biosphere Reserve, Caribbean region, Mexico

Tony Wu / Fin whale (Balaenoptera physalus) lower jaw bones of an exhumed 18 metres long carcass, Tokyo, Japan, November 2013

Tony Wu / Sperm whale (Physeter macrocephalus) male jaw bone showing teeth, Nantucket Whaling Museum, Massachusetts, USA.

James Dunbar / Leaf cutter ant (Atta sp.) Guadeloupe National Park, Guadeloupe, Leeward Islands.

Pete Oxford / Aimara (Hoplias aimara) skull, Dadanawa Ranch (a cattle ranch, one of the largest private ranches in the world) South Rupununi savanna, Guyana, South America

Pete Oxford / Aimara (Hoplias aimara) skull, Dadanawa Ranch (a cattle ranch, one of the largest private ranches in the world) South Rupununi savanna, Guyana, South America

Pascal Pittorino / Stag beetle (Lucanus cervus) male resting on a branch, Close up, Lozere, Cevennes, Languedoc Roussillon, France, July.

Lisa Hoffner / Elephant jaw bones collected for study by Save the Elephants (STE) researchers. Samburu National Reserve, Kenya.

Neil Aldridge / Southern white rhinoceros (Ceratotherium simum) scattered bones amongst bushes, Kariega Game Reserve, Eastern Cape Province, South Africa, September.