Does counting species count as taxonomy? On misrepresenting systematics, yet again.

Recent commentary by Costello and collaborators on the current state of the global taxonomic enterprise attempts to demonstrate that taxonomy is not in decline as feared by taxonomists, but rather is increasing by virtue of the rate at which new species are formally named. Having supported their views with data that clearly indicate as much, Costello et al. make recommendations to increase the rate of new species descriptions even more. However, their views appear to rely on the perception of species as static and numerically if not historically equivalent entities whose value lie in their roles as "metrics". As such, their one-dimensional portrayal of the discipline, as concerned solely with the creation of new species names, fails to take into account both the conceptual and epistemological foundations of systematics. We refute the end-user view that taxonomy is on the rise simply because more new species are being described compared with earlier decades, and that, by implication, taxonomic practice is a formality whose pace can be streamlined without considerable resources, intellectual or otherwise. Rather, we defend the opposite viewpoint that professional taxonomy is in decline relative to the immediacy of the extinction crisis, and that this decline threatens not just the empirical science of phylogenetic systematics, but also the foundations of comparative biology on which other fields rely. The allocation of space in top-ranked journals to propagate views such as those of Costello et al. lends superficial credence to the unsupportive mindset of many of those in charge of the institutional fate of taxonomy. We emphasize that taxonomy and the description of new species are dependent upon, and only make sense in light of, empirically based classifications that reflect evolutionary history; homology assessments are at the centre of these endeavours, such that the biological sciences cannot afford to have professional taxonomists sacrifice the comparative and historical depth of their hypotheses in order to accelerate new species descriptions.

Fossil evidence of wing shape in a stem relative of swifts and hummingbirds (Aves, Pan-Apodiformes).

A feathered specimen of a new species of Eocypselus from the Early Eocene Green River Formation of Wyoming provides insight into the wing morphology and ecology in an early part of the lineage leading to extant swifts and hummingbirds. Combined phylogenetic analysis of morphological and molecular data supports placement of Eocypselus outside the crown radiation of Apodiformes. The new specimen is the first described fossil of Pan-Apodiformes from the pre-Pleistocene of North America and the only reported stem taxon with informative feather preservation. Wing morphology of Eocypselus rowei sp. nov. is intermediate between the short wings of hummingbirds and the hyper-elongated wings of extant swifts, and shows neither modifications for the continuous gliding used by swifts nor modifications for the hovering flight style used by hummingbirds. Elongate hindlimb elements, particularly the pedal phalanges, also support stronger perching capabilities than are present in Apodiformes. The new species is the smallest bird yet described from the Green River Formation, and supports the hypothesis that a decrease in body size preceded flight specializations in Pan-Apodiformes. The specimen also provides the first instance of melanosome morphology preserved in association with skeletal remains from the Green River Formation.

Vivid snapshots of the pastOtherlands Thomas Halliday Random House, 2022. 416 pp.

A paleontologist offers an immersive look at pivotal moments in Earth's history.

Oldest Finch-Beaked Birds Reveal Parallel Ecological Radiations in the Earliest Evolution of Passerines.

Beak shape plays a key role in avian radiations and is one of the most intensely studied aspects of avian evolution and ecology [1-4]. Perhaps no other group is more closely associated with the study of beak shape than Passeriformes (passerines or perching birds), the most species-rich ordinal clade of modern birds. However, despite their extraordinary present-day diversity, our understanding of early passerine evolution has been hindered by their sparse fossil record [5, 6]. Here, we describe two new species of early Eocene stem passerines from the Green River Formation of the United States and the Messel Formation of Germany. These species are the oldest fossil birds to exhibit a finch-like beak and provide the earliest evidence for a diet focused on small, hard seeds in crown birds. Given that granivory is a key adaptation that allows passerines to exploit open temperate environments, it is notable that both species occurred in subtropical environments [7, 8]. Phylogenetic analyses place both species within the Psittacopedidae, an extinct Eocene clade of zygodactyl stem passeriforms that also includes the slender-beaked nectarivorous Pumiliornis, the short-beaked Psittacopes, and the thrush-beaked Morsoravis. Our results reveal that stem passerines attained a diversity of beak shapes paralleling many of the morphotypes present in extant passerine finches, thrushes, and sunbirds, more than 35 million years before these morphotypes arose in the crown group. Extinction of these ecologically diverse fossil taxa may be linked to more sophisticated nest construction in anisodactyl crown passerines versus cavity-nesting in Eocene zygodactyl stem passerines [9].

Comparative and developmental functional morphology of the jaws of living and fossil gars (Actinopterygii: Lepisosteidae).

The feeding mechanism of gars (Ginglymodi : Lepisosteidae) is characterized by cranial elevation and lower jaw rotation but minimal cranial kinesis. Gar jaws have numerous, sharply pointed, elongate teeth for capture of evasive prey. Their mandibles range from relatively short to extremely long depending on the species. Jaw length and lever dimensions were hypothesized to affect the biomechanics of force and motion during feeding, according to simple mechanical models of muscles exerting force through first- or third-order levers. A morphometric protocol was used to measure the jaw structure of seven living and five fossil species of gar and these data were used to calculate the mechanical advantage (a measure of force transmission) for both opening and closing of the mandible. Gars were found to possess low mechanical advantage (MA) and high transmission of motion, although gars occupy a range of biomechanical states across the continuum of force vs. velocity transmission. The long-nose gar, Lepisosteus osseus, has one of the lowest jaw closing MAs (0.05) ever measured in fishes. Intraspecific lever mechanics were also calculated for a developmental series (from feeding larvae to adults) of L. osseus and Atractosteus spatula. A characteristic ontogenetic curve in MA of the lower jaw was obtained, with a large decrease in MA between larva and juvenile, followed by a steady increase during adult growth. This curve correlates with a change in prey type, with the small, robust-jawed individuals feeding mainly on crustaceans and insects and the large, long-jawed individuals of all species becoming mainly piscivorous. Principal components analysis of functionally important morphometrics shows that several gar species occupy different regions of functional morphospace. Some fossil gar species are also placed within functional morphospace using this approach.