Unidad de Paleontología, Departamento de Biología, Universidad Autónoma de Madrid, Madrid, Spain.
Centro para la Integración en Paleobiología (CIPb-UAM), Madrid, Spain.
PeerJ. 2024 May 31;12:e17436. doi: 10.7717/peerj.17436. eCollection 2024.
Postmortem body curvature introduces error in fish morphometric data. Compared to living fish, the causes of such body curvature in fossils may be due to additive taphonomic processes that have been widely studied. However, a protocol that helps to correct its effect upon morphometric data remains unexplored. Here, we test two different mathematical approaches (multivariate regression and the so-called 'unbending functions') available to tackle fish geometric morphometric data in two exceptionally preserved gonorynchiformes fossil fishes, and , from the Las Hoyas deposits (Early Cretaceous, Spain). Although both methods successfully correct body curvature (., removing misleading geometric variation), our results show that traditional approaches applied in living fishes might not be appropriate to fossil ones, because of the additional anatomical alterations. Namely, the best result for 2D fossil fishes is achieved by correcting the arching of the specimens (mathematically "unbending" them). Ultimately, the effect of body curvature on morphometric data is largely taxon independent and morphological diversity mitigates its effect, but size is an important factor to take into account (because larger individuals tend to be less curved).
死后身体弯曲会给鱼类形态计量学数据带来误差。与活体鱼相比，化石中出现这种身体弯曲的原因可能是由于已经得到广泛研究的附加化石化作用。然而，一种有助于纠正其对形态计量数据影响的方案仍未得到探索。在这里，我们测试了两种不同的数学方法（多元回归和所谓的“去弯曲函数”），以处理来自拉斯霍亚斯矿床（早白垩世，西班牙）的两种保存异常完好的弓鳍鱼目化石鱼 和 的几何形态计量学数据。尽管这两种方法都成功地纠正了身体弯曲（即消除了误导性的几何变化），但我们的结果表明，由于额外的解剖学变化，传统方法可能不适用于化石鱼类。具体来说，对于二维化石鱼类，通过校正标本的拱起（从数学上讲是“去弯曲”它们）可以获得最佳效果。最终，身体弯曲对形态计量数据的影响在很大程度上与分类群无关，形态多样性可以减轻其影响，但大小是一个需要考虑的重要因素（因为较大的个体往往弯曲程度较小）。
