Data from: Body shape diversity in Triassic‒Early Cretaceous neopterygian fishes: sustained holostean disparity and predominantly gradual increases in teleost phenotypic variety

Comprising Holostei and Teleostei, the ~32,000 species of neopterygian
fishes are anatomically disparate and represent the dominant group of
aquatic vertebrates today. However, the pattern by which teleosts rose to
represent almost all of this diversity, while their holostean sister group
dwindled to 8 extant species and two broad morphologies, is poorly
constrained. A geometric morphometric approach was taken to generate a
morphospace from over 400 fossil taxa, representing almost all articulated
neopterygian taxa known from the first 150 million years—roughly 60%—of
history (Triassic‒Early Cretaceous). Patterns of morphospace occupancy and
disparity are examined in order to: assess evidence for a phenotypically
'dominant' holostean phase; evaluate whether expansions in
teleost phenotypic variety are predominantly abrupt or gradual, including
assessment of whether apomorphy-defined teleosts are as morphologically
conservative as typically assumed; compare diversification in crown and
stem teleosts. The systematic affinities of dapediiforms and
pycnodontiforms, two extinct neopterygian clades of uncertain phylogenetic
placement, significantly impact patterns of morphological diversification.
For instance, alternative placements dictate whether or not holosteans
possessed statistically higher disparity than teleosts in the Late
Triassic and Jurassic. Despite this ambiguity, all scenarios agree that
holosteans do not exhibit a decline in disparity during the Early
Triassic‒Early Cretaceous interval, but instead maintain their
Toarcian‒Callovian variety until the end of the Early Cretaceous without
substantial further expansions. After a conservative Induan‒Carnian phase,
teleosts colonize (and persistently occupy) novel regions of morphospace
in a predominantly gradual manner until the Hauterivian, after which
expansions are rare. Furthermore, apomorphy-defined teleosts possess
greater phenotypic variety than typically assumed. Comparison of crown and
stem teleost partial disparity indicates that, despite substantial
expansion in crown teleosts between the Late Jurassic and earliest
Cretaceous, stem teleosts remained important long-term contributors to
overall teleost disparity during this time.

新鳍鱼类包含全骨鱼类（Holostei）和真骨鱼类（Teleostei）两大类群，现存约32000个物种，其解剖结构差异显著，是当今水生脊椎动物的优势类群。然而，真骨鱼类如何逐渐占据这一多样性的绝大多数，而其姐妹群全骨鱼类却锐减至仅8个现存物种及两种主要形态，这一演化模式的约束证据尚不充分。本研究采用几何形态测量学（geometric morphometric）方法，基于400余个化石类群构建形态空间；这些类群几乎涵盖了新鳍鱼类演化史前1.5亿年（约占其历史的60%，即三叠纪至早白垩世）所有已知的关节保存完好的类群。研究分析了形态空间的占据模式与差异度，旨在：1）验证全骨鱼类是否存在表型‘主导’阶段的证据；2）评估真骨鱼类表型多样性的扩张以突发为主还是渐进为主，包括检验基于衍征定义的真骨鱼类是否如通常假设那般形态保守；3）比较冠群与干群真骨鱼类的多样化过程。达佩迪鱼目（Dapediiformes）与皮克诺齿鱼目（Pycnodontiformes）是两个系统发育位置尚不明确的已灭绝新鳍鱼类支系，其系统亲缘关系显著影响形态多样化模式的解读。例如，这两类群的不同系统位置归属，将决定晚三叠世至侏罗纪期间全骨鱼类的形态差异度是否在统计上高于真骨鱼类。尽管存在这一不确定性，但所有可能的演化场景均表明：早三叠世至早白垩世期间，全骨鱼类的形态差异度并未下降，而是维持了其在托阿尔期至卡洛维期的多样性水平，直至早白垩世末期，且未出现显著的进一步扩张。真骨鱼类在经历了印度期至卡尼期的保守演化阶段后，以渐进为主的方式占据（并持续保有）形态空间的新区域，这一过程一直持续到欧特里夫期，此后形态扩张极为罕见。此外，基于衍征定义的真骨鱼类具有比通常假设更高的表型多样性。对冠群与干群真骨鱼类的部分差异度比较显示：尽管晚侏罗世至早白垩世早期冠群真骨鱼类的形态差异度显著扩张，但此期间干群真骨鱼类仍是整体真骨鱼类差异度的重要长期贡献者。