#brachiopods

Need a light? Ask for a lampshell! Also known as toenail shells, these shelled filter-feeders are not clams or mollusks, but belong to a phylum all their own called Brachiopoda. This group is one of the oldest on the planet, having survived roughly unchanged since the Cambrian period. Unlike bivalves, they have an asymmetrical top and bottom shell; the top is said to resemble an oil lamp, and the long 'foot', or pedicle, resembles a wick!

Tableau des Animaux et des Végétaux Éxistans Avant le Déluge, Rédigé d'après Cuvier, Buckland, de Humboldt etc. par Perrot, Ingénr.-Geographe. Dessiné d'après les Végétaux et les Fossiles existants dans les divers Cabinets de l'Europe, a wall chart illustrating Antideluvian creatures by Aristide Michel Perrot (1844)

Key (spellings updated): 1. ‎Tree ferns 2. Reeds 3. Bamboo 4. Bladderwrack 5. Polyps 6. Crinoids 7. Trilobites 8. Productus 9. Spirifer 10. Turtles 11. Hemiptera 12. Coleoptera 13. Neuroptera 14. Scorpions 15. Squid 16. Palms 17. Lepidodendron 18. Latanier palms 19. Horsetails 20. Ammonites 21. Terebratula 22. Gryphaea 23. Amblypterus 24. Ophisurus 25. Platinx 26. Cestracion [now Heterodontus] 27. Dapedium 27. Megalosaurus 28. Plesiosaur 29. Ichthyosaur 30. Pterodactyl 31. Crocodiles 32. Iguanodon 33. Lobster 34. Sea Urchins 35. Heron 36. Stork 37. Ibis 38. Zamites and other genera of the Cycads family. 39. Turtles 40. Manatee 41. Whale 42. Dolphin 43. Cerites [?Cerithium] 44. Oysters 45. Belemnites 46. Nautilus 47. Limnaea 48. Planorbis 49. Sea urchins 50. Palaeotherium 51. Common Anoplotherium 52. Light Anoplotherium 53. Hippopotamus 54. [Missing?] 55. Tapir 56. Bear 57. Hyena 58. Tiger 59. Beaver 60. Squirrel 61. Hare 62. Water Rat 63. Owl 64. Thuyas 65. Araucaria Pines 66. Mastodon 67. Deinotherium 68. Mammoth 69. Megaloceros 70. Megatherium 71. Megalonyx 72. Wolf 73. Badger 74. Mole 75. Bat

he is In His Element 💪🪨

Brachiopods are any interesting animals. They look like clams and other bivalves but are more closely related to cuttlefish.

6 of the 8 families of brachiopods existed in the Ordovician Period. Here's a few of the brachiopods you'll find in Ordovician rocks:

Platystrophia

Herbertella

Rafinesquina

Where did brachiopods come from? Well, one hypothesis, the "brachiopod fold" hypothesis suggests that brachiopods evolved from an ancestor similar to Halkieria, a slug-like animal with "chain mail" on its back and a shell at the front and rear end. The hypothesis proposes that the first brachiopod converted its shells into a pair of valves by folding the rear part of its body under its front.

Halkeria

However, fossils from 2007 onwards have supported a new interpretation of the Early-Cambrian tommotiids, and a new hypothesis that brachiopods evolved from tommotiids.

Studies seem to suggest that Halkeria is closer to molluscs while tommotiids are more closely related to brachiopods.

Sadly, at the end of the Paleozoic, 2/3 of the brachiopods wet extinct and they haven't been the same since. Knoll and Bambach concluded that brachiopods were one of several groups that were most vulnerable to the Permian–Triassic extinction, as all had calcareous hard parts (made of calcium carbonate) and had low metabolic rates and weak respiratory systems.

Today, there are three classes of brachiopods left: Lingulata,

Craniata,

and Rhynchonellata.

1. Hylolitha

They're essentially brachiopods with conical shells. The unique feature is the helens, a pair of spiral-shaped calcerous growths near the head which support the body and keep their lophophore above the substrate

2. Agmata

We don't know much about these animals due to the lack of any soft tissue, but we do have the shells; these were conical in shape and were mostly filled with grains of mineral detritus that were absorbed into the body. The minerals were arranged by size, with the largest at the shell wall and the smallest in the middle, and were formed into distinct layers

3. Vetulicolia

"Silicified brachipods. All specimens from Permian limestones of the Glass Mountains, Brewster County, Texas."

From Fossils: An Introduction to Prehistoric Life (1962) by William Henry Matthews.