The phylogeny of Hildoceratidae (Cephalopoda, Ammonitida) resolved by an integrated coding scheme of the conch

Abstract

Ammonite phylogeny has mainly been established based on a stratigraphic approach, with cladistics underconsidered. The main arguments against the use of cladistics are the supposed large amount of homoplasy and the small number of characters. Resolving the phylogeny of the Hildoceratidae (Early Jurassic) is especially challenging because of its large diversity and disparity. Many forms that have not been determined as closely related in previous studies exhibit very similar shapes. Moreover, some groups are morphologically very different, adding difficulties to building a unique coding scheme at a low taxonomic resolution (i.e. species). Here we propose an integrated coding scheme of the peristome shape and the ornamentation, allowing an increased level of comparison. The shape of the peristome is used as a new reference to locate ornamental features and propose new homology hypotheses. In total, 105 taxa have been analysed for 47 characters. We code continuous characters by their means and ranges AE one standard deviation. We test two weighting schemes: equal weights standardized by unit range and implied weighting with several concavity constants. This work has led to redefinition of the phylogenetic inclusivenesses of all the hildoceratid subfamilies. The new coding scheme based on peristome shapes provides the fewest homoplastic characters. The schemes appear promising to improve phylogenetic analyses in ammonoids as well as molluscs as a whole by creating a general coding framework.

Phylogeny, time divergence, and historical biogeography of the South AmericanLiolaemus alticolor-bibroniigroup (Iguania: Liolaemidae)

“…S6 ). The use of continuous characters analyzed as such was employed in many previous studies ( Abdala, 2007 ; Álvarez, Moyers Arévalo & Verzi, 2017 ; Barrionuevo, 2017 ; Bardin, Rouget & Cecca, 2017 ; Nájera-Cortazar, Álvarez Castañeda & De Luna, 2015 ; Quinteros, 2013 ; among many others). In the present study, continuous characters employed in morphological analyses assisted to recover the monophyly of the L. alticolor-bibronii group and supported the monophyly of the L. gravenhorsti group.…”

Learning from beautiful monsters: phylogenetic and morphogenetic implications of left-right asymmetry in ammonoid shells

“…The species assigned on the two sides of the specimen from Cénaret (Fig. 2) are either not regarded as close relatives in the empirical phylogeny proposed by Lacroix [29], or are not included in the recent cladistic hypothesis of Bardin et al [38]. This pathological specimen suggests however that the genera Hildoceras and Haugia/Brodieia may be phylogenetically closer than previously expected.…”

Exact distribution of divergence times from fossil ages and tree topologies

“…Tip dating has been increasingly used for this (e.g., Ronquist et al 2012a;Dembo et al 2015;Lee and Yates 2018), but the recent demonstration (Goloboff et al 2018) that most phenotypic characters fit poorly the Markov model of evolution that is currently used in tip dating raises doubts about the reliability of this approach and highlights the interest in developing additional approaches, such as using birth-and-death models. Development of such methods is timely because much progress has been made in the last decades in understanding the phylogeny of extinct taxa, as shown by the growing number of paleontological papers that included relevant phylogenetic analyses (e.g., Romano and Nicosia 2015;Bardin et al 2017;Brocklehurst 2017). In turn, these progresses have triggered exciting developments of various methods to better time-scale paleontological trees (Hopkins et al 2018).…”

“…Our method can be applied to any clade that has a good fossil record and a sufficiently complex phenotype to allow reasonably reliable phylogenetic analyses to be performed. In addition to vertebrates, this includes, minimally, many other metazoan taxa among arthropods (Ronquist et al 2012b), echinoderms (Sumrall 1997) and mollusks (Merle et al 2011;Bardin et al 2017), among others, as well as embryophytes (Corvez et al 2012). With new calibration constraints in these taxa (and possibly others), the timing of diversification of much of the eukaryotic Tree of Life should be much better documented.…”