Trilobite - Walliserops trifurcatus
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ITEM # TRILO-Morocco-0044
$500.00
$500.00
per item
Lower-Middle Devonian
Foum Zguid, Morocco
ITEM # TRILO-Morocco-0044
Nicely preserved example of Walliserops trifurcatus, a genus of spinose phacopid (acastid) trilobite found in Lower to Middle Devonian age rocks from Morocco. All species of Walliserops share, and are famous for, the spectacular three-pronged "trident" that rises from the glabella. Walliserops is most closely related to the genus Comura, and is a member of the Order Phacopida, Famly Acastidae. Trilobites possessed very advanced eyes for arthropods (jointed-legged invertebrates), which you can see on Walliserops; the level of detail preserved in such fossils is just incredible.
Phacopida ("Lens-face") is an order of trilobite that lived from the Ordovician to the Devonian. It is made up of a morphologically diverse group of related suborders. Hollarops merocristata is a member of the family Acastidae.
The origin of the Phacopida order is uncertain. It comprises three suborders (Phacopina, Calymenina, and Cheirurina) which share a distinctive protaspis (developmental stage lacking segments) type. The Cheirurina and Calymenina retain a rostral plate (an apomorphy) but in virtually all Phacopina the free cheeks are yoked as a single piece. This sort of similarity in development suggests phylogenetic unity. The suborder Calymenina is the most primitive of the Phacopida order and shares some characteristics with the order Ptychopariida, though it is not included in the subclass Libristoma.
Phacopida had 8 to 19 thoracic segments and are distinguishable by the expanded glabella, short or absent preglabellar area, and schizochroal (Phacopina) or holochroal (Cheirurina and Calymenina) eyes. Schizochroal eyes are compound eyes with up to around 700 separate lenses. Each lens has an individual cornea which extended into a rather large sclera. The development of schizochroal eyes in phacopid trilobites is an example of post-displacement paedomorphosis. The eyes of immature holochroal Cambrian trilobites were basically miniature schizochroal eyes. In Phacopida, these were retained, via delayed growth of these immature structures (post-displacement), into the adult form.
The function of the trident itself is poorly understood. With the amount of energy and nutrients expended in growing such a large adornment (probably multiple times as the trilobite shed its skin) its function was clearly important. Although a number of suggestions have been made (e.g. sensory apparatus, disguise or protection), the most satisfactory current explanation is that the trident served as "horns" similar to present day beetles.
This specimen is approximately 2 3/4 inches long on a matrix measuring 3 inches by 2 inches.
Foum Zguid, Morocco
ITEM # TRILO-Morocco-0044
Nicely preserved example of Walliserops trifurcatus, a genus of spinose phacopid (acastid) trilobite found in Lower to Middle Devonian age rocks from Morocco. All species of Walliserops share, and are famous for, the spectacular three-pronged "trident" that rises from the glabella. Walliserops is most closely related to the genus Comura, and is a member of the Order Phacopida, Famly Acastidae. Trilobites possessed very advanced eyes for arthropods (jointed-legged invertebrates), which you can see on Walliserops; the level of detail preserved in such fossils is just incredible.
Phacopida ("Lens-face") is an order of trilobite that lived from the Ordovician to the Devonian. It is made up of a morphologically diverse group of related suborders. Hollarops merocristata is a member of the family Acastidae.
The origin of the Phacopida order is uncertain. It comprises three suborders (Phacopina, Calymenina, and Cheirurina) which share a distinctive protaspis (developmental stage lacking segments) type. The Cheirurina and Calymenina retain a rostral plate (an apomorphy) but in virtually all Phacopina the free cheeks are yoked as a single piece. This sort of similarity in development suggests phylogenetic unity. The suborder Calymenina is the most primitive of the Phacopida order and shares some characteristics with the order Ptychopariida, though it is not included in the subclass Libristoma.
Phacopida had 8 to 19 thoracic segments and are distinguishable by the expanded glabella, short or absent preglabellar area, and schizochroal (Phacopina) or holochroal (Cheirurina and Calymenina) eyes. Schizochroal eyes are compound eyes with up to around 700 separate lenses. Each lens has an individual cornea which extended into a rather large sclera. The development of schizochroal eyes in phacopid trilobites is an example of post-displacement paedomorphosis. The eyes of immature holochroal Cambrian trilobites were basically miniature schizochroal eyes. In Phacopida, these were retained, via delayed growth of these immature structures (post-displacement), into the adult form.
The function of the trident itself is poorly understood. With the amount of energy and nutrients expended in growing such a large adornment (probably multiple times as the trilobite shed its skin) its function was clearly important. Although a number of suggestions have been made (e.g. sensory apparatus, disguise or protection), the most satisfactory current explanation is that the trident served as "horns" similar to present day beetles.
This specimen is approximately 2 3/4 inches long on a matrix measuring 3 inches by 2 inches.