Symphysurus ebbestadi & Calyxdendrum amicabilis n. sp.
Era: Paleozoic
Period: Lower Ordovician
Stage: Tremadocian (485.4 - 477.7 mya)
Location: Beni Zouli, Drâa-Tafilalet region, Zagora Province, Morocco
Coordinates: 30°29'33.6"N 5°53'07.2"W (Same quarry as Marrellidae)
Matrix measurements: 176 x 122 x 170 mm / 6,92" x 4,8" x 0,66"
Trilobite Measurements: 46 x 31 mm / 1,81 x 1,45"
Weight: 635 g / 1,4 lb
Descripción: A unique association of Symphysurus ebbestadi and a planktonic colony of the dendroid (graptolite) Calyxdendrum amicabilis n. sp. We've never seen it before. This fossil has been expertly sandblasted. 100% natural, with no repairs, spines from other trilobites, or paint.
 
The genus Calyxdendrum is revised here to include planktonic dendroid graptolites from the Ordovician (Tremadocian to Sandbian). The massive occurrence of Calyxdendrum amicabilis n. sp. in the Fezouata biota represents one of the few occurrences of dendroid-shaped synrhabdosomes ever discovered. The compound structures, formed by about four to six slender conical tubars of the species, appear as umbrella-shaped synrhabdosomes. In these, the individual tubars are connected by their short nemas to form an irregularly shaped proximal membrane. The species occurs in the late Tremadocian Sagenograptus murrayi biozone of the Bou Izargane section on the Ternata Plain north of Zagora, Morocco. The mass occurrence is interpreted as representing planktonic colonies of dendroids transported by low-velocity currents or actively moving toward different water regions across a broad, shallow shelf region.
(Source: https://revistes.ub.edu/index.php/GEOACTA/article/view/45607)
 
The Fezouata Formation, or Fezouata Shale, contains extraordinary fossils because the animals were quickly buried by storm deposits of silt and clay, favorable conditions for the preservation of soft tissue (now pyritized or altered by a mixture of iron oxides and hydroxides, hence their orange-red color). The fossils belong to two intervals, the Tremadocian and the Floian, which are much less fossil-rich.
 
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