The three-dimensionally articulated oral apparatus of a Devonian heterostracan sheds light on feeding in Palaeozoic jawless fishes.

Attempts to explain the origin and diversification of vertebrates have commonly invoked the evolution of feeding ecology, contrasting the passive suspension feeding of invertebrate chordates and larval lampreys with active predation in living jawed vertebrates. Of the extinct jawless vertebrates that phylogenetically intercalate these living groups, the feeding apparatus is well-preserved only in the early diverging stem-gnathostome heterostracans. However, its anatomy remains poorly understood. Here, we use X-ray microtomography to characterize the feeding apparatus of the pteraspid heterostracan Rhinopteraspis dunensis (Roemer, 1855). The apparatus is composed of 13 plates arranged approximately bilaterally, most of which articulate from the postoral plate. Our reconstruction shows that the oral plates were capable of rotating around the transverse axis, but likely with limited movement. It also suggests the nasohypophyseal organs opened internally, into the pharynx. The functional morphology of the apparatus in Rhinopteraspis precludes all proposed interpretations of feeding except for suspension/deposit feeding and we interpret the apparatus as having served primarily to moderate the oral gape. This is consistent with evidence that at least some early jawless gnathostomes were suspension feeders and runs contrary to macroecological scenarios that envisage early vertebrate evolution as characterized by a directional trend towards increasingly active food acquisition.

Hagfish genome elucidates vertebrate whole-genome duplication events and their evolutionary consequences.

Polyploidy or whole-genome duplication (WGD) is a major event that drastically reshapes genome architecture and is often assumed to be causally associated with organismal innovations and radiations. The 2R hypothesis suggests that two WGD events (1R and 2R) occurred during early vertebrate evolution. However, the timing of the 2R event relative to the divergence of gnathostomes (jawed vertebrates) and cyclostomes (jawless hagfishes and lampreys) is unresolved and whether these WGD events underlie vertebrate phenotypic diversification remains elusive. Here we present the genome of the inshore hagfish, Eptatretus burgeri. Through comparative analysis with lamprey and gnathostome genomes, we reconstruct the early events in cyclostome genome evolution, leveraging insights into the ancestral vertebrate genome. Genome-wide synteny and phylogenetic analyses support a scenario in which 1R occurred in the vertebrate stem-lineage during the early Cambrian, and 2R occurred in the gnathostome stem-lineage, maximally in the late Cambrian-earliest Ordovician, after its divergence from cyclostomes. We find that the genome of stem-cyclostomes experienced an additional independent genome triplication. Functional genomic and morphospace analyses demonstrate that WGD events generally contribute to developmental evolution with similar changes in the regulatory genome of both vertebrate groups. However, appreciable morphological diversification occurred only in the gnathostome but not in the cyclostome lineage, calling into question the general expectation that WGDs lead to leaps of bodyplan complexity.

The oldest three-dimensionally preserved vertebrate neurocranium.

The neurocranium is an integral part of the vertebrate head, itself a major evolutionary innovation1,2. However, its early history remains poorly understood, with great dissimilarity in form between the two living vertebrate groups: gnathostomes (jawed vertebrates) and cyclostomes (hagfishes and lampreys)2,3. The 100 Myr gap separating the Cambrian appearance of vertebrates4-6 from the earliest three-dimensionally preserved vertebrate neurocrania7 further obscures the origins of modern states. Here we use computed tomography to describe the cranial anatomy of an Ordovician stem-group gnathostome: Eriptychius americanus from the Harding Sandstone of Colorado, USA8. A fossilized head of Eriptychius preserves a symmetrical set of cartilages that we interpret as the preorbital neurocranium, enclosing the fronts of laterally placed orbits, terminally located mouth, olfactory bulbs and pineal organ. This suggests that, in the earliest gnathostomes, the neurocranium filled out the space between the dermal skeleton and brain, like in galeaspids, osteostracans and placoderms and unlike in cyclostomes2. However, these cartilages are not fused into a single neurocranial unit, suggesting that this is a derived gnathostome trait. Eriptychius fills a major temporal and phylogenetic gap in our understanding of the evolution of the gnathostome head, revealing a neurocranium with an anatomy unlike that of any previously described vertebrate.

MEDREV (pharmacy-health psychology intervention in people living with dementia with behaviour that challenges): the feasibility of measuring clinical outcomes and costs of the intervention.

BACKGROUND: People living with dementia in care homes frequently exhibit "behaviour that challenges". Anti-psychotics are used to treat such behaviour, but are associated with significant morbidity. This study researched the feasibility of conducting a trial of a full clinical medication review for care home residents with behaviour that challenges, combined with staff training. This paper focusses on the feasibility of measuring clinical outcomes and intervention costs. METHODS: People living with moderate to severe dementia, receiving psychotropics for behaviour that challenges, in care homes were recruited for a medication review by a specialist pharmacist. Care home and primary care staff received training on the management of challenging behaviour. Data were collected at 8 weeks, and 3 and 6 months. Measures were Neuropsychiatric Inventory-Nursing Home version (NPI-NH), cognition (sMMSE), quality of life (EQ-5D-5 L/DEMQoL) and costs (Client Services Receipt Inventory). Response rates, for clinical, quality of life and health economic measures, including the levels of resource-use associated with the medication review and other non-intervention costs were calculated. RESULTS: Twenty-nine of 34 participants recruited received a medication review. It was feasible to measure the effects of the complex intervention on the management of behaviour that challenges with the NPI-NH. There was valid NPI-NH data at each time point (response rate = 100%). The sMMSE response rate was 18.2%. Levels of resource-use associated with the medication review were estimated for all 29 participants who received a medication review. Good response levels were achieved for other non-intervention costs (100% completion rate), and the EQ-5D-5 L and DEMQoL (≥88% at each of the time points where data was collected). CONCLUSIONS: It is feasible to measure the clinical and cost effectiveness of a complex intervention for behaviour that challenges using the NPI-NH and quality of life measures. TRIAL REGISTRATION: ISRCTN58330068. Retrospectively registered, 15 October 2017.

Preparing care home staff to manage challenging behaviours among residents living with dementia: A mixed-methods evaluation.

We evaluated an intervention designed to manage challenging behaviours of people with dementia. Framework analysis of interviews (n = 21) showed the intervention modified practice and perceptions. The intervention (n = 58; power calculation proposed n = 160 for medium effect) had no significant effect on attitudes to dementia for time (p = .42) or care home (p = .15). The Maslach burnout scores did not change significantly for person-centredness for time (p = .83) or care home (p = .29). Hope scores showed a significant effect post-intervention (p = .004), but this was not maintained. No significant main effect was found for care home (p = .36). Experiential learning enabled staff to experience benefits of person-centred care firsthand.

Bite marks and predation of fossil jawless fish during the rise of jawed vertebrates.

Although modern vertebrate diversity is dominated by jawed vertebrates, early vertebrate assemblages were predominantly composed of jawless fishes. Hypotheses for this faunal shift and the Devonian decline of jawless vertebrates include predation and competitive replacement. The nature and prevalence of ecological interactions between jawed and jawless vertebrates are highly relevant to both hypotheses, but direct evidence is limited. Here, we use the occurrence and distribution of bite mark type traces in fossil jawless armoured heterostracans to infer predation interactions. A total of 41 predated specimens are recorded; their prevalence increases through time, reaching a maximum towards the end of the Devonian. The bite mark type traces significantly co-occur with jawed vertebrates, and their distribution through time is correlated with jawed vertebrate diversity patterns, particularly placoderms and sarcopterygians. Environmental and ecological turnover in the Devonian, especially relating to the nekton revolution, have been inferred as causes of the faunal shift from jawless to jawed vertebrates. Here, we provide direct evidence of escalating predation from jawed vertebrates as a potential contributing factor to the demise and extinction of ostracoderms.

Medication review plus person-centred care: a feasibility study of a pharmacy-health psychology dual intervention to improve care for people living with dementia.

BACKGROUND: "Behaviour that Challenges" is common in people living with dementia, resident in care homes and historically has been treated with anti-psychotics. However, such usage is associated with 1800 potentially avoidable deaths annually in the UK. This study investigated the feasibility of a full clinical trial of a specialist dementia care pharmacist medication review combined with a health psychology intervention for care staff to limit the use of psychotropics. This paper focuses on feasibility; including recruitment and retention, implementation of medication change recommendations and the experiences and expectations of care staff. METHODS: West Midlands care homes and individuals meeting the inclusion criteria (dementia diagnosis; medication for behaviour that challenges), or their personal consultee, were approached for consent. A specialist pharmacist reviewed medication. Care home staff received an educational behaviour change intervention in a three-hour session promoting person-centred care. Primary healthcare staff received a modified version of the training. The primary outcome measure was the Neuropsychiatric Inventory-Nursing Home version at 3 months. Other outcomes included quality of life, cognition, health economics and prescribed medication. A qualitative evaluation explored expectations and experiences of care staff. RESULTS: Five care homes and 34 of 108 eligible residents (31.5%) were recruited, against an original target of 45 residents across 6 care homes. Medication reviews were conducted for 29 study participants (85.3%) and the pharmacist recommended stopping or reviewing medication in 21 cases (72.4%). Of the recommendations made, 57.1% (12 of 21) were implemented, and implementation (discontinuation) took a mean of 98.4 days. In total, 164 care staff received training and 21 were interviewed. Care staff reported a positive experience of the intervention and post intervention adopting a more holistic patient-centred approach. CONCLUSIONS: The intervention contained two elements; staff training and medication review. It was feasible to implement the staff training, and the training appeared to increase the ability and confidence of care staff to manage behaviour that challenges without the need for medication. The medication review would require significant modification for full trial partly related to the relatively limited uptake of the recommendations made, and delay in implementation. TRIAL REGISTRATION: ISRCTN58330068 . Registered 15 October 2017. Retrospectively registered.

Morphospace saturation in the stem-gnathostomes pteraspidiformes heterostracans: an early radiation of a 'bottom' heavy clade.

Ostracoderms (fossil armoured jawless fishes) shed light on early vertebrate evolution by revealing the step-wise acquisition of jawed vertebrate characters, and were important constituents of Middle Palaeozoic vertebrate faunas. A wide variety of head shield shapes are observed within and between the ostracoderm groups, but the timing of these diversifications and the consistency between different measures of their morphospace are unclear. Here, we present the first disparity (explored morphospace) versus diversity (number of taxa) analysis of Pteraspidiformes heterostracans using continuous and discrete characters. Patterns of taxic diversity and morphological disparity are in accordance: they both show a rise to a peak in the Lochkovian followed by a gradual decline in the Middle-Late Devonian. Patterns are largely consistent for disparity measures using sum of ranges or total variance, and when using continuous or discrete characters. Pteraspidiformes heterostracans can be classified as a "bottom-heavy clade", i.e., a group where a high initial disparity decreasing over time is detected. In fact, the group explored morphospace early in its evolutionary history, with much of the subsequent variation in dermal armour occurring as variation in the proportions of already evolved anatomical features. This Early Devonian radiation is also in agreement with the paleobiogeographic distribution of the group, with a maximum of dispersal and explored morphospace during the Lochkovian and Pragian time bins.

Parsimony, not Bayesian analysis, recovers more stratigraphically congruent phylogenetic trees.

Reconstructing evolutionary histories requires accurate phylogenetic trees. Recent simulation studies suggest that probabilistic phylogenetic analyses of morphological data are more accurate than traditional parsimony techniques. Here, we use empirical data to compare Bayesian and parsimony phylogenies in terms of their congruence with the distribution of age ranges of the component taxa. Analysis of 167 independent morphological data matrices of fossil tetrapods finds that Bayesian trees exhibit significantly lower stratigraphic congruence than the equivalent parsimony trees. As such, taking stratigraphic data as an independent benchmark indicates that parsimony analyses are more accurate for phylogenetic reconstruction of morphological data. The discrepancy between simulated and empirical studies may result from historic data peaking practices or some complexities of empirical data as yet unaccounted for.

Discriminating signal from noise in the fossil record of early vertebrates reveals cryptic evolutionary history.

The fossil record of early vertebrates has been influential in elucidating the evolutionary assembly of the gnathostome bodyplan. Understanding of the timing and tempo of vertebrate innovations remains, however, mired in a literal reading of the fossil record. Early jawless vertebrates (ostracoderms) exhibit restriction to shallow-water environments. The distribution of their stratigraphic occurrences therefore reflects not only flux in diversity, but also secular variation in facies representation of the rock record. Using stratigraphic, phylogenetic and palaeoenvironmental data, we assessed the veracity of the fossil records of the jawless relatives of jawed vertebrates (Osteostraci, Galeaspida, Thelodonti, Heterostraci). Non-random models of fossil recovery potential using Palaeozoic sea-level changes were used to calculate confidence intervals of clade origins. These intervals extend the timescale for possible origins into the Upper Ordovician; these estimates ameliorate the long ghost lineages inferred for Osteostraci, Galeaspida and Heterostraci, given their known stratigraphic occurrences and stem-gnathostome phylogeny. Diversity changes through the Silurian and Devonian were found to lie within the expected limits predicted from estimates of fossil record quality indicating that it is geological, rather than biological factors, that are responsible for shifts in diversity. Environmental restriction also appears to belie ostracoderm extinction and demise rather than competition with jawed vertebrates.