This review asks some hard questions about what the enigmatic graphoglyptid trace fossils are, documents some of their early fossil record from the Ediacaran-Cambrian transition and explores the idea that they may not have been fossils at all. Most researchers have considered the Graphoglyptida to have had a microbial-farming mode of life similar to that proposed for the fractal Ediacaran Rangeomorpha. This begs the question “What are the Graphoglyptida if not the Rangeomorpha persevering” and if so then “What if…?”. This provocative idea has at its roots some fundamental questions about how to distinguish burrows sensu-stricto from the external molds of endobenthic sediment displacive organisms.

Considering that life on earth evolved about 3.7 billion years ago, vertebrates are young, appearing in the fossil record during the Cambrian explosion about 542 to 515 million years ago. Results from sequence analyses of genomes from bacteria, yeast, plants, invertebrates and vertebrates indicate that receptors for adrenal steroids (aldosterone, cortisol), and sex steroids (estrogen, progesterone, testosterone) also are young, with an estrogen receptor and a 3-ketosteroid receptor first appearing in basal chordates (cephalochordates: amphioxus), which are close ancestors of vertebrates. Through gene duplication and divergence of the 3-ketosteroid receptor, receptors that respond to androgens, glucocorticoids, mineralocorticoids and progestins evolved in vertebrates. Thus, an ancestral progesterone receptor and an ancestral corticoid receptor, the common ancestor of the glucocorticoid and mineralocorticoid receptors, evolved in jawless vertebrates (cyclostomes: lampreys, hagfish). This was followed by evolution of an androgen receptor, distinct glucocorticoid and mineralocorticoid receptors and estrogen receptor-α and -β in cartilaginous fishes (gnathostomes: sharks). Further evolution of mineralocorticoid signaling occurred with the evolution of aldosterone synthase in lungfish, a forerunner of terrestrial vertebrates. Adrenal and sex steroid receptors are not found in echinoderms: and hemichordates, which are ancestors in the lineage of cephalochordates and vertebrates. The evolution of steroid receptors at key nodes in the evolution of vertebrates, in which steroid receptors act as master switches to regulate differentiation, development, reproduction, immune responses, electrolyte homeostasis and stress responses, argues for an important role for steroid receptors in the evolutionary success of vertebrates, considering that the human genome contains about 22,000 genes, which is not much larger than genomes of invertebrates, such as Caenorhabditis elegans (~18,000 genes) and Drosophila (~14,000 genes).

The taxonomy of trilobites Abadiella Hupé, 1953 and Parabadiella Zhang, 1966 from the lower Cambrian of Gondwana has long been a controversy. Based on newly-collected and formerly-reported materials, 94 trilobite cranidia within 21 species are selected for morphometric analyses: principal components analysis (PCA) and canonical variates analysis (CVA). The integrated morphological characters are successfully accounted for by two principal components in PCA. The further validations for the presupposed qualitative groupings are indispensable to detect and calibrate the ultimate taxonomic results in CVA. By this way, all specimens distributed in a consistent morphospace in PCA and the short distances between them demonstrate their close morphological affinity, supporting their congeneric status within Abadiella. Additionally, three morphotypes were recognized from all selected specimens and they were eventually revised and incorporated into A. bourgini Hupé, 1953, A. huoi Zhang, 1966, and A. yunnanensis Luo, 1981, through stepwise test-calibration to get a high correct rate as far as possible in CVA. From this, it is certain that A. huoi is conspecific in South Australia and South China. Its occurrence allows to correlate the Australian A. huoi Range Zone to the identical zone in South China (in platform), having an approximately consistent stratigraphic range in the two regions. In comparison with A. huoi, A. bourgini was reported from fewer localities in South China. Nevertheless, its presence in the Daguinaspis Zone of Issendalenian Stage in Morocco permits a correlation with Chinese and Australian A. huoi Zone. As an auxiliary marker for A. huoi, the occurrence of A. bourgini in Morocco, South Australia and South China reinforce the correlation potential and resolution in species-level for the Cambrian Stage 3 in Gondwana region.

Glacial ripping is a newly recognized process sequence in which subglacial erosion is triggered by groundwater overpressure. Investigations in gneiss terrain in lowland Sweden indicate that ripping involves three stages of (i) hydraulic jacking, (ii) rock disruption under subglacial traction and (iii) glacial transport of rock blocks. Evidence for each stage includes, respectively, dilated fractures with sediment fills, disintegrated roches moutonnées and boulder spreads. Here we ask: can glacial ripping also occur in sedimentary rocks, and, if so, what are its effects? The case study area is in hard, thinly bedded, gently dipping Cambrian quartz-arenites at Loch Eriboll, NW Scotland. Field surveys reveal dilated, sediment filled, bedding-parallel fractures, open joints and brecciated zones, interpreted as markers for pervasive, shallow penetration of the quartz-arenite by water at over-pressure. Other features, including disintegrated rock surfaces, boulder spreads and monomict rubble tills, indicate glacial disruption and short distance subglacial transport. The field results, together with published cosmogenic isotope ages, indicate that glacial ripping operated with high impact close to the former ice margin at Loch Eriboll at 17.6-16.5 ka. Glacial ripping thus can operate effectively in bedded, hard sedimentary rocks and the accompanying brecciation is significant – if not dominant - in till formation. Candidate markers for glacial ripping are identified in other sedimentary terrains in former glaciated areas of the Northern Hemisphere.

The more than thirty spacetime theorems developed over the past five decades establish that the universe and its spacetime dimensions have emerged from a cause/Causal Agent beyond the cosmos. Thus, to infer that this cause/Causal Agent may have intervened in the origin and history of Earth and Earth’s life resides well within the bounds of reason. Meanwhile, proponents of each of the three prevailing naturalistic models for the origin and history of Earth’s life have marshalled arguments and evidence that effectively undermine and refute the other two models. A biblical perspective and approach to Earth’s life can help resolve this impasse. While a superficial and pervasive appeal to divine intervention thwarts scientific advance, so does a rigid adherence to naturalism. A productive way forward is to identify which models (or parts of models), whether naturalistic, theistic, or a combination, most effectively narrow, rather than widen, knowledge gaps, minimize anomalies, offer the most comprehensive and detailed explanation of the data, and prove most successful in predicting scientific discoveries.

Deuterostomes make a sudden appearance in the fossil record during the Early Cambrian. Two deuterostome groups, the chordates and the vetulicolians, are of particular interest for understanding the evolutionary dynamics of the Cambrian evolutionary event. Lagerstätten in China and elsewhere have dramatically improved our understanding of the range of variation in these ancient animals. Cephalochordate and vertebrate body plans are well established at least by Cambrian Series 2. Taken together, roughly a dozen chordate genera and fifteen vetulicolian genera document an explosive radiation of deuterostomes at the base of the Cambrian. A new vetulicolian (••• nov. gen. nov. sp.) with a polygonal anterior section and a narrow, unsegmented posterior region (‘tail’) bearing possible myotomes provides new insight into the affinities of the various body plans that emerged during the Early Cambrian. It seems clear that the advent of deuterostomes near the Cambrian boundary involved both a reversal of gut polarity and a two-sided retinoic acid gradient, with a gradient discontinuity at the midpoint of the organism that is reflected in the sharp division of vetulicolians into anterior and posterior sections.