Injured trilobites within a collection of dinosaurs: Using the Royal Tyrrell Museum of Palaeontology to document Cambrian predation

Biomineralised exoskeletons of trilobites are ideal for recording abnormalities, documenting injuries from failed attacks, and understanding predation in the fossil record. The illustration of new injured Cambrian-aged trilobites is particularly important for elucidating aspects of early Paleozoic predator-prey systems and identifying groups that were targets of this early predation. We document six new abnormal trilobite specimens from the Royal Tyrrell Museum of Palaeontology, including the first evidence for injuries on the corynexochid trilobite Hemirhodon amplipyge. These new data highlight the importance of museum collections in uncovering unique and informative specimens for studies of predation on early animals

Malformed trilobites from the Ordovician and Devonian

Trilobite malformations are often ascribed to failed predation and represent key evidence for Paleozoic arthropod predator–prey systems. A large number of malformed trilobites are known to Cambrian-aged deposits and have recently been discussed at length. Conversely, most post-Cambrian records are noted as anecdotal points within larger taxonomic works. To expand the consideration of post-Cambrian injured trilobites, we report two malformed Ogygiocarella debuchii specimens from the Middle Ordovician of Wales and a heavily malformed Spiniscutellum umbelliferum specimen from the Early Devonian of the Czech Republic. These specimens are considered to represent records of failed predation. In considering these specimens, we explore possible injury-making groups, in particular noting that S. umbelliferum was likely prey for multiple apex predators. Continued examination of injured trilobites represents the main direction for uncovering how this iconic group of biomineralised arthropods interacted with higher tropic levels within Paleozoic foodwebs

Taphonomy and taxonomy of a juvenile lambeosaurine (Ornithischia: Hadrosauridae) bonebed from the late Campanian Wapiti Formation of northwestern Alberta, Canada

Hadrosaurid (duck-billed) dinosaur bonebeds are exceedingly prevalent in upper Cretaceous (Campanian–Maastrichtian) strata from the Midwest of North America (especially Alberta, Canada, and Montana, U.S.A) but are less frequently documented from more northern regions. The Wapiti Formation (Campanian–Maastrichtian) of northwestern Alberta is a largely untapped resource of terrestrial palaeontological information missing from southern Alberta due to the deposition of the marine Bearpaw Formation. In 2018, the Boreal Alberta Dinosaur Project rediscovered the Spring Creek Bonebed, which had been lost since 2002, along the northern bank of the Wapiti River, southwest of Grande Prairie. Earlier excavations and observations of the Spring Creek Bonebed suggested that the site yielded young hadrosaurines. Continued work in 2018 and 2019 recovered ~300 specimens that included a minimum of eight individuals, based on the number of right humeri. The morphology of several recovered cranial elements unequivocally supports lambeosaurine affinities, making the Spring Creek sample the first documented occurrence of lambeosaurines in the Wapiti Formation. The overall size range and histology of the bones found at the site indicate that these animals were uniformly late juveniles, suggesting that age segregation was a life history strategy among hadrosaurids. Given the considerable size attained by the Spring Creek lambeosaurines, they were probably segregated from the breeding population during nesting or caring for young, rather than due to different diet and locomotory requirements. Dynamic aspects of life history, such as age segregation, may well have contributed to the highly diverse and cosmopolitan nature of Late Cretaceous hadrosaurids

KMUP-1 activates BK(Ca) channels in basilar artery myocytes via cyclic nucleotide-dependent protein kinases

1. This study investigated whether KMUP-1, a synthetic xanthine-based derivative, augments the delayed-rectifier potassium (K(DR))- or large-conductance Ca(2+)-activated potassium (BK(Ca)) channel activity in rat basilar arteries through protein kinase-dependent and -independent mechanisms. 2. Cerebral smooth muscle cells were enzymatically dissociated from rat basilar arteries. Conventional whole cell, perforated and inside-out patch-clamp electrophysiology was used to monitor K(+)- and Ca(2+) channel activities. 3. KMUP-1 (1 μM) had no effect on the K(DR) current but dramatically enhanced BK(Ca) channel activity. This increased BK(Ca) current activity was abolished by charybdotoxin (100 nM) and iberiotoxin (100 nM). Like KMUP-1, the membrane-permeable analogs of cGMP (8-Br-cGMP) and cAMP (8-Br-cAMP) enhanced the BK(Ca) current. 4. BK(Ca) current activation by KMUP-1 was markedly inhibited by a soluble guanylate cyclase inhibitor (ODQ 10 μM), an adenylate cyclase inhibitor (SQ 22536 10 μM), competitive antagonists of cGMP and cAMP (Rp-cGMP, 100 μM and Rp-cAMP, 100 μM), and cGMP- and cAMP-dependent protein kinase inhibitors (KT5823, 300 nM and KT5720, 300 nM). 5. Voltage-dependent L-type Ca(2+) current was significantly suppressed by KMUP-1 (1 μM), and nearly abolished by a calcium channel blocker (nifedipine, 1 μM). 6. In conclusion, KMUP-1 stimulates BK(Ca) currents by enhancing the activity of cGMP-dependent protein kinase, and in part this is due to increasing cAMP-dependent protein kinase. Physiologically, this activation would result in the closure of voltage-dependent calcium channels and the relaxation of cerebral arteries