De novo assembly of a chromosome-level reference genome for the California Scrub-Jay, Aphelocoma californica.

We announce the assembly of the first de novo reference genome for the California Scrub-Jay (Aphelocoma californica). The genus Aphelocoma comprises four currently recognized species including many locally adapted populations across Mesoamerica and North America. Intensive study of Aphelocoma has revealed novel insights into the evolutionary mechanisms driving diversification in natural systems. Additional insights into the evolutionary history of this group will require continued development of high-quality, publicly available genomic resources. We extracted high molecular weight genomic DNA from a female California Scrub-Jay from northern California and generated PacBio HiFi long-read data and Omni-C chromatin conformation capture data. We used these data to generate a de novo partially phased diploid genome assembly, consisting of two pseudo-haplotypes, and scaffolded them using inferred physical proximity information from the Omni-C data. The more complete pseudo-haplotype assembly (arbitrarily designated "Haplotype 1") is 1.35 Gb in total length, highly contiguous (contig N50 = 11.53 Mb), and highly complete (BUSCO completeness score = 97%), with comparable scaffold sizes to chromosome-level avian reference genomes (scaffold N50 = 66.14 Mb). Our California Scrub-Jay assembly is highly syntenic with the New Caledonian Crow reference genome despite ~10 million years of divergence, highlighting the temporal stability of the avian genome. This high-quality reference genome represents a leap forward in publicly available genomic resources for Aphelocoma, and the family Corvidae more broadly. Future work using Aphelocoma as a model for understanding the evolutionary forces generating and maintaining biodiversity across phylogenetic scales can now benefit from a highly contiguous, in-group reference genome.

A draft reference genome of the red abalone, Haliotis rufescens, for conservation genomics.

Red abalone, Haliotis rufescens, are herbivorous marine gastropods that primarily feed on kelp. They are the largest and longest-lived of abalone species with a range distribution in North America from central Oregon, United States, to Baja California, MEX. Recently, red abalone have been in decline as a consequence of overharvesting, disease, and climate change, resulting in the closure of the commercial fishery in the 1990s and the recreational fishery in 2018. Protecting this ecologically and economically important species requires an understanding of their current population dynamics and connectivity. Here, we present a new red abalone reference genome as part of the California Conservation Genomics Project (CCGP). Following the CCGP genome strategy, we used Pacific Biosciences HiFi long reads and Dovetail Omni-C data to generate a scaffold-level assembly. The assembly comprises 616 scaffolds for a total size of 1.3 Gb, a scaffold N50 of 45.7 Mb, and a BUSCO complete score of 97.3%. This genome represents a significant improvement over a previous assembly and will serve as a powerful tool for investigating seascape genomic diversity, local adaptation to temperature and ocean acidification, and informing management strategies.

Multiregional Sequencing Analysis Reveals Extensive Genetic Heterogeneity in Gastric Tumors from Latinos.

Gastric cancer is a leading cause of cancer mortality and health disparities in Latinos. We evaluated gastric intratumoral heterogeneity using multiregional sequencing of >700 cancer genes in 115 tumor biopsies from 32 patients, 29 who were Latinos. Analyses focused on comparisons with The Cancer Genome Atlas (TCGA) and on mutation clonality, druggability, and signatures. We found that only approximately 30% of all mutations were clonal and that only 61% of the known TCGA gastric cancer drivers harbored clonal mutations. Multiple clonal mutations were found in new candidate gastric cancer drivers such as EYS, FAT4, PCDHA1, RAD50, EXO1, RECQL4, and FSIP2. The genomically stable (GS) molecular subtype, which has the worse prognosis, was identified in 48% of our Latino patients, a fraction that was >2.3-fold higher than in TCGA Asian and White patients. Only a third of all tumors harbored clonal pathogenic mutations in druggable genes, with most (93%) GS tumors lacking actionable clonal mutations. Mutation signature analyses revealed that, in microsatellite-stable (MSS) tumors, DNA repair mutations were common for both tumor initiation and progression, while tobacco, POLE, and inflammation signatures likely initiate carcinogenesis. MSS tumor progression was likely driven by aging- and aflatoxin-associated mutations, as these latter changes were usually nonclonal. In microsatellite-unstable tumors, nonclonal tobacco-associated mutations were common. Our study, therefore, contributed to advancing gastric cancer molecular diagnostics and suggests clonal status is important to understanding gastric tumorigenesis. Our findings of a higher frequency of a poor prognosis associated molecular subtype in Latinos and a possible new aflatoxin gastric cancer etiology also advance cancer disparities research. Significance: Our study contributes to advancing our knowledge of gastric carcinogenesis, diagnostics, and cancer health disparities.

Use of Paley Classification and SUPERankle Procedure in the Management of Fibular Hemimelia.

BACKGROUND: Fibular hemimelia is the most common deficiency involving the long bones. Paley classification is based on the ankle joint morphology, identifies the basic pathology, and helps in planning the surgical management. Reconstruction surgery encompasses foot deformity correction and limb length equalization. The SUPERankle procedure is a combination of bone and soft tissue procedures that stabilizes the foot and addresses all deformities. METHODS: We retrospectively reviewed 29 consecutive patients (29 limb segments), surgically treated between December 2000 and December 2014. Among the 29 patients, 27 were treated with reconstructive procedures. Type 1 (8 patients) cases were treated with only limb lengthening, and correction of tibial deformities. Type 2 (7 patients) cases were treated by distal tibial medial hemiepiphysiodesis or supramalleolar varus osteotomy. In type 3 (10 patients) cases, the foot deformity was corrected using the SUPERankle procedure. Type 4 (2 patients) cases were treated with supramalleolar osteotomy along with posteromedial release and lateral column shortening. In a second stage, limb lengthening was performed, using the Ilizarov technique. In the remaining 2 patients (type 3A and type 3C), amputation was performed using Syme technique as a first choice of treatment. RESULTS: The results were evaluated using Association for the Study and Application of Methods of Ilizarov scoring. Excellent results were obtained in 15 of 27 (55%) patients. Six (22%) patients had good results, 4 (14.8%) had fair results, and 2 (7%) had poor results. Mean limb length discrepancy at initial presentation was 3.55 cm (range: 2 to 5.5 cm) which significantly improved to 1.01 cm (range: 0 to 3 cm) after treatment (P=0.015). CONCLUSIONS: Our results and a review of the literature clearly suggest that limb reconstruction according to Paley classification, is an excellent option in the management of fibular hemimelia. Our 2-staged procedure (SUPERankle procedure followed by limb lengthening) helps in reducing the complications of limb lengthening and incidence of ankle stiffness. Performing the first surgery at an earlier age (below 5 y) plays a significant role in preventing recurrent foot deformities. LEVEL OF EVIDENCE: Level IV.

Accuracy of valgus osteotomy using dynamic hip screw.

BACKGROUND: Non-union of neck femur is a common but difficult situation to manage especially in young adults. There are two main options of arthroplasty or osteotomy. The aim of this study was to assess the results of intertrochanteric valgus osteotomy in non-union femoral neck fractures. PATIENTS AND METHODS: We present a study of 44 cases of neck femur non-union including untreated fractures, late presentations (more than 3 weeks), treated with compression screw, DHS. From 2006-2016, 44 patients presented to our institute and we analyzed them prospectively on the following criteria: Pauwel's angle, Garden classification, union at fracture site, union at osteotomy site, osteoporosis and AVN changes. Inclusion criteria were age<65, neck not reabsorbed, no AVN. Powel's angle was calculated using the anatomic axis of femur. Wedge angle is equal to Powel's angle minus 30 degree. Entry point of DHS was at the base of greater trochanter and tip of the screw was in the inferior quadrant. Y osteotomy was done in the distal half of the lesser trochanter with a proximal straight cut. RESULTS: Complete union was noted in 93% of the cases. One patient with uncontrolled diabetes developed severe infection and was treated with excision arthoplasty. AVN occurred in 3 cases. The Powell's angle was reduced to mean 30 (22-39). The neck shaft angle was increased to mean 140 (130-150). Limp was noted in almost all patients but they were able to walk full weight bearing with or without the support of a stick. CONCLUSION: Valgus intertrochanteric osteotomy achieved good union rates and good functional outcome with minimal complications.

Use of a raft construct through a locking plate without bone grafting for split-depression tibial plateau fractures.

PURPOSE: To review the outcome after open reduction and internal fixation using a periarticular raft construct through a locking plate without bone grafting for split-depression tibial plateau fractures. METHODS: Records of 38 knees in 31 men and 7 women aged 25 to 75 (mean, 42.7) years who underwent open reduction and internal fixation using a periarticular raft construct through a locking plate without use of a bone graft or bone substitute for split-depression (>5 mm) proximal tibial plateau fractures (Schatzker type II or AO/OTA type 4.1 B3) were reviewed. The integrity of the articular surface was assessed using radiographs. The Rasmussen radiological score and clinical score, the Lysholm knee score, and the Tegner activity score were also assessed. RESULTS: The mean follow-up period was 22.8 (range, 6-36) months. All patients achieved bone union after a mean of 13.2 (range, 8-26) weeks. The mean range of motion was 118º (range, 100º-130º). The Rasmussen radiological score was excellent in 27 patients, good in 9, and fair in 2. The Rasmussen clinical score was excellent in 15 patients, good in 21, and fair in 2. The Lysholm knee score was excellent in 26 patients, good in 8, and fair in 4. 32 of the 38 patients recovered to their preoperative Tegner activity scores. Only one patient with severe comminution had loss of reduction after full weightbearing. CONCLUSION: Fixation using a periarticular raft construct through a locking plate without use of a bone graft or bone substitute for split-depression proximal tibial plateau fractures is a viable option.

A retrospective review of cancer treatments and outcomes among Inuit referred from Nunavut, Canada.

BACKGROUND: Cancer is a health concern in Inuit populations. Unique cultural, dietary, and genetic factors and geographic isolation influence cancer epidemiology in this group. Inuit-specific data about oncology treatments and survival outcomes in Canadian Inuit referred to urban treatment centres are lacking. METHODS: A retrospective chart review of Inuit patients referred to The Ottawa Hospital Cancer Centre (tohcc) from the Baffin region of Nunavut between 2000 and 2010 was conducted. Nunavut cancer registry data were used to establish the percentage of cancer cases referred and their survival outcomes. RESULTS: Of 307 cancer patients registered among Baffin-region Inuit, 216 [70% (63 men, 153 women)] were referred to tohcc for chemotherapy (ct) and radiation therapy (rt). Mean age in the referred group was 59.3 years (range: 25-89 years), and current smokers constituted half the group (52%). The cancers most commonly leading to referral in men were lung (55%), colorectal (19%), and nasopharyngeal (11%) cancers; in women, they were lung (46%), colorectal (24%), breast (10%), nasopharyngeal (6%), and cervical (5%) cancers. Of the 216 referred patients, 82 (38%) had already undergone surgery, and 18 (8%) received chemoradiation or rt only, all given with curative intent. Among the surgical patients referred, 33 (40%) and 23 (28%) went on to receive adjuvant ct and adjuvant rt respectively. Among 116 patients referred for palliative care, 64 (55%) received ct, 76 (66%) received rt, 43 (37%) received both ct and rt, and 19 (16%) received neither treatment. Median all-stage overall survival was 10 months for patients with lung cancer [95% confidence interval: 6.1 to 13.9 months] and 37 months for patients with colorectal cancer [95% confidence interval: 14.8 to 59.2 months]. CONCLUSIONS: High uptake of palliative and adjuvant ct and rt was observed in the Inuit patients referred to tohcc. Lung cancer was the most common cancer in referred Inuit men and women. The survival rates for Inuit lung cancer patients referred to tohcc were comparable to those in the rest of Canada. Further research is required to understand reasons for non-referral of Canadian Inuit to tohcc.

Correction of coronal plane deformities around the knee using a tension band plate in children younger than 10 years.

BACKGROUND: Guided growth through temporary hemiepiphysiodesis has gained acceptance as the preferred primary treatment in treating pediatric lower limb deformities as it is minimally invasive with a lesser morbidity than the traditional osteotomy. The tension band plate is the most recent development in implants used for temporary hemiepiphysiodesis. Our aim was to determine its safety and efficacy in correcting coronal plane deformities around the knee in children younger than 10 years. MATERIALS AND METHODS: A total of 24 children under the age of 10 were operated for coronal plane deformities around the knee with a single extra periosteal tension band plate and two nonlocking screws. All the children had a pathological deformity for which a detailed preoperative work-up was carried out to ascertain the cause of the deformity and rule out physiological ones. The average age at hemiepiphysiodesis was 5 years 3 months (range: 2 years to 9 years 1 month). RESULTS: The plates were inserted for an average of 15.625 months (range: 7 months to 29 months). All the patients showed improvement in the mechanical axis. Two patients showed partial correction. Two cases of screw loosening were observed. In the genu valgum group, the tibiofemoral angle improved from a preoperative mean of 19.89° valgus (range: 10° valgus to 40° valgus) to 5.72° valgus (range: 2° varus to 10° valgus). In patients with genu varum the tibiofemoral angle improved from a mean of 28.27° varus (range: 13° varus to 41° varus) to 1.59° valgus (range: 0-8° valgus). CONCLUSION: Temporary hemiepiphysiodesis through the application of the tension band plate is an effective method to correct coronal plane deformities around the knee with minimal complications. Its ease and accuracy of insertion has extended the indication of temporary hemiepiphysiodesis to patients younger than 10 years and across a wide variety of diagnosis including pathological physis, which were traditionally out of the purview of guided growth.

Effects of weather and heliophysical conditions on emergency ambulance calls for elevated arterial blood pressure.

We hypothesized that weather and space weather conditions were associated with the exacerbation of essential hypertension. The study was conducted during 2009-2010 in the city of Kaunas, Lithuania. We analyzed 13,475 cards from emergency ambulance calls (EACs), in which the conditions for the emergency calls were made coded I.10-I.15. The Kaunas Weather Station provided daily records of air temperature (T), wind speed (WS), relative humidity, and barometric pressure (BP). We evaluated the associations between daily weather variables and daily number of EACs by applying a multivariate Poisson regression. Unfavorable heliophysical conditions (two days after the active-stormy geomagnetic field or the days with solar WS>600 km/s) increased the daily number of elevated arterial blood pressure (EABP) by 12% (RR=1.12; 95% confidence interval (CI) 1.04-1.21); and WS≥3.5 knots during days of T<1.5 °C and T≥12.5 °C by 8% (RR=1.08; CI 1.04-1.12). An increase of T by 10 °C and an elevation of BP two days after by 10 hPa were associated with a decrease in RR by 3%. An additional effect of T was detected during days of T≥17.5 °C only in females. Women and patients with grade III arterial hypertension at the time of the ambulance call were more sensitive to weather conditions. These results may help in the understanding of the population's sensitivity to different weather conditions.

Antegrade interlocking nailing versus dynamic compression plating for humeral shaft fractures.

PURPOSE: To compare antegrade interlocking nailing with dynamic compression plating for humeral shaft fractures in terms of functional outcomes, union and complication rates. METHODS: 34 men and 22 women aged >18 years with fresh humeral shaft fractures (up to grade IIIa) with or without neurological deficits underwent either antegrade interlocking nailing (n=31) or dynamic compression plating (n=25). Functional outcome of the upper limbs (according to the American Shoulder and Elbow Surgeons [ASES] score), pain, rates of union, and complications in the 2 groups were compared. RESULTS: Respectively in the nailing and plating groups, mean operating times were 65 and 112 minutes (p<0.001), mean blood loss volumes were 20 and 232 ml (p<0.001), mean ASES scores were 31.4 and 29.0 (p=0.448), complication rates were 20% (6/31) and 24% (6/25) [p=0.900], non-union rates were 13% (4/31) and 8% (2/25) [p=0.625], and delayed union rates were 7% (2/31) and 4% (1/25) [p=0.787]. CONCLUSION: Both techniques were appropriate for treating humeral shaft fractures.

Intramedullary nailing supplemented with Poller screws for proximal tibial fractures.

PURPOSE: To evaluate outcome of intramedullary nailing supplemented with Poller screws for proximal tibial fractures using small diameter nails. METHODS: 50 men and 20 women (75 fractures) aged 18 to 65 (mean, 33) years underwent intramedullary nailing supplemented with Poller screws for acutely displaced fractures (n=60) or for delayed union (n=10) or mal-union (n=5) of the proximal metadiaphyseal tibia. 88% of the fractures were caused by road traffic accidents. 54 cases had closed fractures and 21 had grade I or II compound fractures. Clinical and radiological outcome was evaluated. RESULTS: In 69 cases, healing occurred after a mean of 4.2 (range, 3-9) months. In 5 cases, there was non-union, which was resolved by bone grafting. One case was mal-united. 63 patients recovered a full range of knee motion (0º-130º), and the remaining 7 attained flexion of 0º to 90º. According to the knee rating scale of the Hospital for Special Surgery, outcome was excellent in 50 patients, good in 14, poor in 3, and failed in 3 at month 12, and remained so after a mean follow-up of 30.8 months. Postoperatively, 74 cases had <5º of varus or valgus malalignment, and only one developed varus of +7º. 65 cases exhibited no deformity, 7 had a deformity of <3º, and 3 had a deformity of 4º to 9º. CONCLUSION: Poller screws help maintain fixation of intramedullary nailing and alignment of fractures.

The disparity of priapulid, archaeopriapulid and palaeoscolecid worms in the light of new data.

Priapulids and their extinct relatives, the archaeopriapulids and palaeoscolecids, are vermiform, carnivorous ecdysozoans with an armoured, extensible proboscis. These worms were an important component of marine communities during the Palaeozoic, but were especially abundant and diverse in the Cambrian. Today, they comprise just seven genera in four families. Priapulids were among the first groups used to test hypotheses concerning the morphological disparity of Cambrian fossils relative to the extant fauna. A previous study sampled at the generic level, concluding that Cambrian genera embodied marginally less morphological diversity than their extant counterparts. Here, we sample predominantly at the species level and include numerous fossils and some extant forms described in the last fifteen years. Empirical morphospaces for priapulids, archaeopriapulids and palaeoscolecids are relatively insensitive to changes in the taxon or character sample: their overall form has altered little, despite the markedly improved sampling. Cambrian and post-Cambrian genera occupy adjacent rather than broadly overlapping regions of these spaces, and Cambrian species still show lower morphological disparity than their post-Cambrian counterparts. Crucially, the significance of this difference has increased with improved taxon sampling over research time. In contrast with empirical morphospaces, the phylogeny of priapulids, archaeopriapulids and palaeoscolecids derived from morphological characters is extremely sensitive to details of taxon sampling and the manner in which characters are weighted. However, the extant Priapulidae and Halicryptidae invariably resolve as sister families, with this entire clade subsequently being sister group to the Maccabeidae. In our most inclusive trees, the extant Tubiluchidae are separated from these other living taxa by a number of small, intervening fossil clades.

Arsenic-resistant Pseudomonas spp. and Bacillus sp. bacterial strains reducing As(V) to As(III), isolated from Alps soils, Italy.

Five arsenic-resistant bacterial strains (designated MP1400, MP1400a, MP1400d, APSLA3, and BPSLA3) were isolated from soils collected at the Alps region (Italy), which showed no contamination by arsenic. Phylogenetic analysis of the 16S rRNA gene sequences assigned them to the genera Pseudomonas and Bacillus. Bacillus sp. strain 1400d and Pseudomonas spp. strains APSLA3 and MP1400 showed higher tolerance to As(III), as indicated by minimum inhibitory concentrations of 10 mmol/L. Pseudomonas sp. strain MP1400 exhibited higher tolerance to As(V) (minimum inhibitory concentration of 135 mmol/L). The isolated arsenic-resistant strains were able to reduce As(V) to As(III), especially Pseudomonas sp. strain MP1400 reducing 2 mmol/L of As(V) to As(III) within 24 h. The results suggest that the isolated bacterial strains play a role in the arsenic biogeochemical cycle of arsenic-poor soils in the Alps mount area.

Arsenic precipitation by an anaerobic arsenic-respiring bacterial strain isolated from the polluted sediments of Orbetello Lagoon, Italy.

AIMS: To isolate and characterize an anaerobic bacterial strain from the deeper polluted lagoon sediment able to use as electron acceptors [As(V)] and sulfate (SO4(2-)), using lactate as an electron donor. METHODS AND RESULTS: Methods for isolation from polluted lagoon sediments included anaerobic enrichment cultures in the presence of As(V) and SO4(2-). Reduction of As(V) to As(III) was observed during the growth of the bacterial strain, and the final concentration of As(III) was lower than the initial As(V) one, suggesting the immobilization of As(III) in the yellow precipitate. The precipitate was identified by energy dispersive spectroscopy X-ray as arsenic sulfide. Scanning electron microscopy (SEM) revealed rod-shaped bacterial cells embedded in the precipitate, where net-like formations strictly related to the bacterial cells were visible. The surface of the precipitate showed the adhesion of bacterial cells, forming clusters. Transmission electron microscopy (TEM) also highlighted precipitates inside the bacterial cells and on their surface. Following 16S rRNA sequencing, the bacterial strain 063 was assigned to the genus Desulfosporosinus. CONCLUSIONS: This study reports, for the first time, the isolation from the polluted lagoon sediments of a strain capable of respiring and using As(V) and SO4(2-) as electron acceptors with lactate as the sole carbon and energy source with the formation of an arsenic sulfide precipitate. SIGNIFICANCE AND IMPACT OF THE STUDY: The identification of these properties provides novel insight into the possible use of the anaerobic strain in bioremediation processes and also adds to the knowledge on the biogeochemical cycling of arsenic.

Birth outcomes following prenatal exposure to antidepressants.

BACKGROUND: Antidepressant use during pregnancy and the peripartum period is common despite the absence of clear evidence-based guidelines to direct clinical use of these compounds. METHOD: We compared obstetrical and neonatal outcomes as recorded in medical records among 84 pregnant women with major depressive or anxiety disorders (DSM-IV criteria) who took antidepressants during pregnancy (cases) versus a 2:1 age- and parity-matched control group of 168 unexposed women. Women in the case group had sought psychiatric consultation regarding the use of medication from the Perinatal and Reproductive Psychiatry Program at the Massachusetts General Hospital between 1996 and 2000. RESULTS: There were no significant differences among cases versus controls and their offspring, with respect to various neonatal and obstetrical outcomes, including gestational age and weight, although 1-minute Apgar scores were slightly lower in exposed infants. Admissions to the special care nursery were more frequent, but briefer and based on relatively minor indications, among case newborns. There were no significant differences in neonatal outcomes between exposures to serotonin reuptake inhibitor (SRI) and tricyclic (TCA) antidepressants. CONCLUSION: This retrospective cohort study found no evidence of major increases in risk of adverse obstetrical or neonatal outcomes following prenatal exposure to antidepressants, nor between SRIs and TCAs. Larger, prospective studies with specific neurobehavioral measures are required to resolve current uncertainties about safe and effective use of antidepressants by pregnant women.

Bupropion SR for the treatment of postpartum depression: a pilot study.

Despite the prevalence of postpartum depression, few studies have assessed the efficacy of antidepressants for the treatment of this disorder. Failure to treat postpartum depression (PPD) places the woman at risk for chronic depression and may have adverse effects on child wellbeing and development. Eight female outpatients aged 18-45 yr were enrolled in an 8-wk open-label trial of bupropion SR for PPD. All patients met DSM-IV criteria for major depression with onset within 3 months of delivery and scored 17 or greater on the Hamilton Depression Rating Scale (HAMD) at baseline. Those with onset of depressive symptoms during pregnancy, psychotic symptoms, or significant medical illness were excluded. Median scores on the HAMD declined from 20.5 (range 15-38) at baseline to 10.0 (range 1-20) at end-point (p<0.05, Wilcoxon signed-ranks test; LOCF). Six out of the eight subjects demonstrated a > or =50% decrease in HAMD scores from baseline; three subjects achieved remission (HAMD score of < or =7) at week 8. Median final dosage of bupropion SR was 262.5 (range 37.5-300). Bupropion SR was well tolerated, and no subjects discontinued treatment as a result of medication side-effects. Bupropion SR represents an effective and well-tolerated antidepressant for the treatment of PPD.

Nice snake, shame about the legs.

Snakes are one of the most extraordinary groups of terrestrial vertebrates, with numerous specializations distinguishing them from other squamates (lizards and their allies). Their musculoskeletal system allows creeping, burrowing, swimming and even gliding, and their predatory habits are aided by chemo- and thermoreceptors, an extraordinary degree of cranial kinesis and, sometimes, powerful venoms. Recent discoveries of indisputable early fossil snakes with posterior legs are generating intense debate about the evolutionary origin of these reptiles. New cladistic analyses dispute the precise significance and phylogenetic placement of these fossils. These conflicting hypotheses imply radically different scenarios of snake origins and relationships with wide biological implications.

Brief review of the stylophoran debate.

The "calcichordate" theory interprets an extinct group of calcite-plated invertebrates, the stylophorans, as chordates. In this theory, comute stylophorans are interpreted as stem chordates, whereas mitrate stylophorans are primitive members of the acraniates, tunicates, and craniates. However, this theory discounts major synapomorphies between comutes and mitrates. These groups constitute a natural, monophyletic group which is here argued to lie within the echinoderm radiation. The "calcichordate" theory is, therefore, rejected because it relies on assumption-driven hypotheses of character transformation which are supported by ambiguous, poor, or missing fossil evidence. Stylophorans may lie at the base of the echinoderm clade and primitively lack pentameral symmetry, therefore casting light on the near-ancestral body organization of the phylum.