Some arboreal monocotyledons, such as the dragon trees (Dracaena sp.), can develop impressive trunks (>5 m perimeter) through a lateral meristem, but their ages are difficult to determine. We report here a series of calibrated radiocarbon (14C) dates obtained from a stem section of Dracaena draco (L.) L. subsp. draco growing on the island of Tenerife, Canary Islands, Spain. This radial section, about 40 cm long, was cut on October 18, 2023, from a large (∼60 cm diameter) branch that had fallen off the main stem of a privately owned dragon tree. In order to apply 14C calibration, and given the lack of clearly defined growth layers, we collected 33 sequential samples at ∼1-cm intervals along this radial section. A first attempt at wiggle-matching resulted in a calibrated dating of ∼1787 CE for the innermost sample. Because we only knew the spatial distance, but not the time interval, between 14C dates, we further applied calibration tools commonly used for sedimentary sequences. The Poisson-process deposition model in the software OxCal resulted in a calibrated age for the innermost sample of 1776–1798 CE (2σ). The classic and Bayesian age-depth deposition models available as R packages dated the innermost sample to, respectively, 1775–1862 and 1768–1813 CE. Because the branch was at a height of ∼3 m from the ground, and its section did not reach the pith, our results suggest that this dragon tree was ∼300 years old in 2023.

Paleoecological reconstructions provide valuable insights into the impacts of environmental change on key functions of wetland ecosystems. Here, we integrate biological and sedimentological proxies to provide a baseline of vegetation and hydrological change since the Middle Holocene at a riparian marsh, with the goal of informing wetland restoration within a regional biodiversity hotspot in the Great Lakes coastal zone. Four stages of wetland development are identified, reflecting the combined impacts of Lake Erie fluctuations, fluvial processes, regional paleoclimate, and anthropogenic influence. Wetland establishment took place ∼6000 cal yr BP during a Lake Erie high stand, and pollen assemblages indicate that the site was initially a forested wetland. Subsequently, water levels remained elevated as a transition to an emergent marsh with silty, organic-rich sediments took place ∼5300 cal yr BP. Once water levels stabilized in the Late Holocene, a thicket swamp established in sandier sediments, suggesting closer proximity to the meandering channel. The intensification of European settlement from 1850 CE marked a major transition, resulting from disturbances caused by land clearance and hydrological alterations, including higher rates of sediment accretion, novel diatom communities, and increases in herbaceous vegetation. These paleoecological records demonstrate the importance of considering whole-watershed measures in restoration planning, including controls on mineral sediment influxes, maintenance of local water tables, and management of invasive species producing high biomass.

Understanding biotic responses to environmental changes will help identify extinction risks and direct conservation efforts to mitigate negative effects associated with anthropogenic-induced environmental changes. Here we use the Quaternary fossil record of mole salamanders (Ambystoma) from the southwestern United States and northern Mexico to reveal geographic patterns of extirpation since the Pleistocene. Ambystoma are known to have previously inhabited regions of central Texas on the Edwards Plateau; however, they are largely absent from the region today. We used a well-dated fossil record of Ambystoma from Hall’s Cave combined with other fossil sites in the region to deduce why Ambystoma was ultimately extirpated from the Edwards Plateau and to test hypotheses related to temperature-driven body-size changes in line with the temperature–size rule. We propose that Ambystoma was likely extirpated from the region due to changing temperature and precipitation regimes that caused increased mortality and disruptions to breeding and larval development. We found some support for decreased body size in Ambystoma with increased temperature during the late Pleistocene, suggesting that body size may be an important feature to monitor in modern populations of Ambystoma as salamanders become subjected to increasingly hotter temperatures in the coming decades.

Terrestrial gastropods can incorporate carbon from multiple sources, including 14C-depleted carbonate from limestone, known as the “Limestone Problem” (Goodfriend and Stipp 1983). This affects the reliability of 14C dating on terrestrial snails, and varies by species, habitat, and physiography, necessitating local validation studies. This study assessed whether two land snail taxa common in carbonate terrains of Florida (USA) accurately reflect atmospheric 14C concentration at the time of biomineralization, a necessary condition for accurate dating, or if they incorporate pre-aged carbon, leading to radiocarbon ages that are “too old.” Radiocarbon measurements were made on 11 modern, known-age specimens (collected 1967–2015) of the rosy wolfsnail (Euglandina rosea) and flatcoil (Polygyra spp.) snails, and results were compared to expected atmospheric values based on the Bomb21 NH2 calibration dataset (Hua et al. 2022). Specimens from carbonate terrains had significantly lower 14C activity than the contemporaneous atmosphere, while those from sandy terrains showed no such offsets. The magnitude of the offset varied by taxon. Flatcoils from carbonate terrains had the most unreliable dates, overestimated by 1350 ± 740 14C yr on average. Rosy wolfsnails from carbonate terrains had smaller offsets, overestimating by 270 ± 130 14C yr on average. The results suggest land snails from Florida will incorporate significant and variable amounts of pre-aged or “dead” carbonate in their shells if it is present in the landscape.

The Proetida likely represent the only surviving trilobite clade past the Devonian mass extinction event(s). Although members of order Proetida have long been studied, the global phylogenetic relationships across this pivotal time are still unresolved. I used a Bayesian phylogenetic approach to construct a subordinal level tree for members within the superfamily Proetoidea. Two models, a relaxed and strict clock model, were compared and used to assess past reconstructions of clades within the order. The trees from both models highlight key relationships among proetides across the Devonian and show paraphyly in groups that have been considered monophyletic in the past. Trees from both models also suggest that major groups, e.g., the genus Gerastos Goldfuss, 1843 and the family Phillispidae (which represents the most diverse post-Devonian proetide group under current taxonomic schemes) are polyphyletic. This in turn suggests, in a paleobiological context, a more complex pattern of survivorship over the Late Devonian than previously suggested as well as pervasive parallelisms toward certain ‘Gerastos’ or ‘phillipsid’ morphotypes.