On fossils, phylogenies and sequences of evolutionary change.
On fossils, phylogenies and sequences of evolutionary change.
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关于化石、系统发育和进化变化的顺序。
DOI：
10.1098/rspb.2014.0115
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Friedman M
中科院分区：
文献类型：
--
作者：
Friedman M
我们感谢Britz等人。[1]他介绍了Houy [2]对后鼻龙（Opisthomyzon）对于现代鼻龙解剖学进化的重要性的有先见之明的解释，并遗憾自己没有发现他的优雅解释[3]。自一个多世纪前发现†后鳅以来，许多著名的鱼类学家都考虑过它的相关性[4-7]，但他们的观察结果都没有接近Houy对与附着盘起源相关的进化转变序列的清晰解释，也没有如此接近地预示着我们自己的结论。因此，我们欢迎我们的同事提供的翻译和他们的评论引起的交流[1]，这些共同给了Houy他应得的长期拖延的认可。然而，我们不同意他们关于我们研究的其他方面的说法。我们的同事评论[1]的一个中心主题是，我们提出的进化序列[3]在面对Houy的建议时变得非常多余。虽然我们同意我们的研究为他的假设轨迹提供了佐证，但目前还不清楚†后吸鳅的系统发育位置和其圆盘的其他原始特征的发现是否代表了过去努力的重复。虽然Houy明确暗示了后鳅属是一种干鳅属[2]，但与Phtheirichthys [6，8]和Echeneis [9]的竞争性比对在他的描述之后突出了过去围绕该化石亲缘关系的不确定性。在最好的情况下，这些替代性的位置在皇冠内使其对椎间盘进化的影响模棱两可。承认过去的努力是科学的基石，但使用新数据和技术对旧思想进行批判性测试也是如此。我们的研究支持并补充了Houy的工作，因为我们进一步记录了后吸鳅的解剖结构并限制了其系统位置。由于没有一个明确的系统发育框架，后吸鳅在后吸鳅附着盘的进化方面仍然保持沉默。毫无疑问，构成后鳅正模标本中可见头骨大部分的成对骨骼是额骨。该化石中标记为顶骨的结构[3]是额骨后部的凹陷特征（而不是参考文献[1]中箭头所示的这些骨化的中间），似乎带有角状突起，可能代表嵴。我们愿意考虑另一种解释，即额骨的后延伸，但以前的作者[2]，我们的同事[1]和我们[3]之间一致认为，前额骨阻止了后颏区大部分头骨的椎间盘前延伸。因此，令人惊讶的是，我们的同事认为我们的分析表明椎间盘的后部位置是次要的。有几个因素可能造成这种混乱，我们欢迎有机会澄清这些因素。我们在后迷索和假设的性格变化序列中提到的“颅后”盘，是为了与现存的颅后迷索的极端情况形成对比，后者的颅上盘延伸到整个头骨，并终止于吻部。我们同意，在<$Opisthomyzon中，不能排除粘连盘和最后颅骨之间的一些微小重叠[1，2]。很明显，我们的术语--旨在表示病情的程度而不是绝对的--可能会被误解，而将<$Opisthomyzon的椎间盘更清楚地描述为位于后方。与前一点相关的是，
We thank Britz et al.[1] for introducing Houy’s [2] prescient interpretation of the significance of† Opisthomyzon for the evolution of modern remora anatomy, and regret not having discovered his elegant account ourselves [3]. Many prominent ichthyologists have considered the relevance of† Opisthomyzon since its discovery more than a century ago [4–7], but none of their observations approaches Houy’s clear explication of the sequence of evolutionary transformations associated with the origin of the adhesion disc or so closely foreshadow our own conclusions. We therefore welcome the translation provided by our co-workers and the exchange arising from their comment [1], which together give Houy the long-delayed recognition he richly deserves. However, we disagree with their claims concerning other aspects of our study. A central theme of our co-workers’ comment [1] is that the evolutionary sequence we proposed [3] is rendered largely redundant when confronted with Houy’s [2] proposal. While we agree that our study provides corroboration for his hypothesized trajectory, it is unclear how robust phylogenetic placement of† Opisthomyzon and discovery of additional primitive features of its disc represent a duplication of past efforts. Although Houy clearly implies† Opisthomyzon is a stem remora [2], competing alignments with Phtheirichthys [6, 8] and Echeneis [9] that postdate his account highlight past uncertainty surrounding the affinities of this fossil. At best, these alternative placements within the remora crown render its implications for the evolution of the disc ambiguous. Recognition of past efforts is a cornerstone of science, but so too is the critical testing of old ideas using new data and techniques. Our study supports and adds to Houy’s work, because we further documented the anatomy of† Opisthomyzon and constrained its systematic position. Without a clear phylogenetic framework,† Opisthomyzon remains mute with respect to the evolution of the remora adhesion disc. There is no doubt that the paired bones constituting the majority of the visible skull in the holotype of† Opisthomyzon are frontals. The structures labelled as parietals in this fossil [3] are depressed features at the rear of the frontals (rather than the middle of these ossifications, indicated by arrows in reference [1]) that appear to bear horn-like projections possibly representing crests. We are willing to consider an alternative interpretation as posterior extensions of the frontals, but what is agreed between previous authors [2], our co-workers [1] and us [3] is that the ornamented frontals preclude anterior extension of the disc over much of the skull in† Opisthomyzon. It is therefore surprising that our co-workers suggest that our analysis shows that the posterior position of the disc is secondary. Several factors might contribute to this confusion, and we welcome the opportunity to clarify them. Our references to ‘postcranial’discs in both† Opisthomyzon and hypothesized sequences of character change were intended as contrasts with the extreme condition in extant remoras, where the supracranial disc extends over the entirety of the skull and terminates at the snout. We agree that some minor overlap between the adhesion disc and the hindmost skull cannot be excluded in† Opisthomyzon [1, 2]. It is obvious how our terminology—meant to indicate degree of condition rather than absolutes—might be misinterpreted, and that the disc in† Opisthomyzon is more clearly described as posteriorly located. Related to this previous point, the three-state character describing fin position in