X-ray microtomography of the late Carboniferous whip scorpions (Arachnida, Thelyphonida) Geralinura britannica and Proschizomus petrunkevitchi
X-ray microtomography of the late Carboniferous whip scorpions (Arachnida, Thelyphonida) Geralinura britannica and Proschizomus petrunkevitchi
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DOI：
10.1080/14772019.2023.2180450
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发表时间：
2023-01
影响因子：
2.6
通讯作者：
R. Garwood;J. Dunlop
中科院分区：
文献类型：
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作者：
R. Garwood;J. Dunlop
鞭蝎(Thelyhonida)和裂殖目(Schizomida)是蜘蛛纲密切相关的两个目，其物种多样性低于其他蜘蛛纲，反映在有限的化石记录中。在这里，我们用X射线显微断层摄影术研究了英国斯塔福德郡科斯利(晚石炭世，约315 Ma)英国中部煤系中的两只关键鞭蝎化石，并将这些分类群合并到一个更新的蜘蛛纲系统发育中。Geralinura brittanicaPocock是一种明确的鞭蝎，其足尖比先前假设的更接近现代条件。大转子有一个背侧凸缘和前背部的牙齿，整个足掌由于至少有一个髌骨隆起的存在而呈近络合状。这些结果表明，自晚石炭世以来，鞭蝎处于高度的停滞状态，Geralinula Scudder属属于冠群，即现存的鞭蝎科。Proschomus petrunkevitchiDunlop和Horrocks缺乏正眼，这是与裂体纲共有的特征，但不同于分裂形纲，足掌也有膝盖骨和胫骨突起；尽管附肢以约45°的角度发音，而不是像现存的鞭蝎那样水平发音，或像分裂形目动物那样垂直发音。我们的系统发育驳斥了之前的一个假设，即P。Petrunkevitchiis是一种茎分裂体，它把它放在鞭蝎中。然而，该物种可能很早就从鞭蝎血统中分枝出来，因此它的形态可能反映了一种半形性的排列，在这种排列中，足掌从更像腿的附肢过渡到完全捕食的、爪状的附肢。
Whip scorpions (Thelyphonida) and schizomids (Schizomida) are closely related arachnid orders, whose low species diversity compared to other arachnid groups is reflected in a limited fossil record. Here we investigate two key fossil whip scorpions from the British Middle Coal Measures of Coseley, Staffordshire (late Carboniferous,c. 315 Ma), UK, using X-ray microtomography, and incorporate the taxa into an updated arachnid phylogeny.Geralinura brittanicaPocock, is an unequivocal whip scorpion, whose pedipalps are closer to the modern condition than previously assumed. The trochanter bears a dorsal flange with prodorsal teeth, and the whole pedipalp is rendered subchelate by the presence of at least a patellar apophysis. These results suggest a high degree of stasis in whip scorpions since the late Carboniferous, and the genusGeralinulaScudder, is within the crown-group; i.e. the extant family Thelyphonidae.Proschizomus petrunkevitchiDunlop and Horrocks, lacks median eyes, a character shared with Schizomida, but unlike schizomids the pedipalp also has patellar and tibial apophyses; albeit with the appendage articulating at an angle ofc.45° rather than articulating horizontally as in living whip scorpions, or vertically as in schizomids. Our phylogeny refutes a previous hypothesis thatP. petrunkevitchiis a stem-schizomid, and places it among the whip scorpions instead. However, the species may have branched early from the whip scorpion lineage, and thus its morphology might reflect a plesiomorphic arrangement in which the pedipalps were transitioning from a more leg-like to a fully raptorial and claw-like set of prey-catching appendages.