Through artificial selection, humans have altered the morphology of domestic dogs and created the range of morphological traits present in the diverse dog breeds seen today. This article tests how artificial breeding for extreme facial reduction affects the craniodental complex in domestic dogs (Canis lupus familiaris). These brachycephalic dog breeds allow for a natural experiment on facial reduction, providing additional insight into this well‐studied phenomenon associated with the evolutionary history of other animals including primates. We used an existing set of clinically obtained CT scans from dogs representing three brachycephalic breeds and a comparative sample. We recorded three‐dimensional coordinate data for 62 cranial and mandibular landmarks that allowed us to analyze differences in shape in the neurocranium, basicranium, and viscerocranium. Through geometric morphometric analysis, we confirmed that most of the cranial shape variance in our sample was associated with cephalic index (cranial width‐to‐length ratio) and reflects the effects of facial reduction. Shape changes in the cranium and mandible co‐vary. We also identified several areas of localized shape change. Whereas the primary shape change seen in the mandible is a uniform shift in proportion involving rostral‐caudal shortening and medial‐lateral widening, the majority of the shape change in the palate is localized to the maxilla. Here, a pronounced difference in maxillary carnassial orientation relative to the mandibular carnassials results in disruption of the functionally important carnassial complex. These results support previous studies showing integration within the skull and highlight the deleterious effects of artificial selection for extreme facial reduction in domestic dogs. Anat Rec, 2019. © 2019 Wiley Periodicals, Inc. Anat Rec, 303:330–346, 2020. © 2019 American Association for Anatomy

The past decade has seen an exponential increase of innovative applications of 3D technology in the geosciences. Here, we present a case study from the Florida Museum of Natural History applied to the multidisciplinary field of paleontology. We have deployed 3D scanning and printing techniques for the purposes of scientific research, formal education, and informal outreach. Depending on the application of the 3D file, different techniques are utilized to create high-fidelity models of physical fossil specimens or geologic field sites. These techniques include X-ray CT scans, surface scans, and photogrammetry, all of which produce 3D models that vary in resolution and scale. Novel paleontological research applied non-destructive CT scanning to explore the internal anatomy of fossil museum specimens, additionally, 3D models are being used to create K–12 curricula aligned with national and state-specific education standards that are implemented in formal classroom settings. Many of these lessons are part of the NSF-funded iDigFossils project, which aims to evaluate students’ motivation and interest towards science, technology, engineering, and mathematics after participating in integrated 3D printing and paleontology lessons. Specifically, lessons on dinosaur trackways, horse evolution, and the Great American Biotic Interchange teach geologic concepts such as deep time, taphonomy, plate tectonics, and evolutionary trends. The same 3D models developed for these K–12 lessons have been used during Florida Museum’s outreach events to engage broad audiences with hands-on exhibits and activities. All 3D files are stored on open-access, online repositories, providing accessibility to fossil specimens and field sites. The application of 3D technology for the study of fossils and paleontology will continue to expand the impact of scientific discoveries for basic research as well as for broader impacts on society.

Domestic dogs (Canis lupus familiaris) exhibit a wide range of cranial morphologies. This diversity in skull shape is largely the result of modern selective breeding practices. This project investigates the impact of selection for facial reduction on canine neuroanatomy. Previous research has indicated that the breeding for reduced faces in dogs has led to global impacts in the shape of their skull and mandible. This previous research has largely failed to consider, however, the impact of these breeding practices on the soft neuroanatomical tissue. We generated endocasts from an existing set of clinically‐obtained CT scans. This sample consists of a variety of dogs with various cranial morphologies representing four known breeds as well as a comparative sample of dogs of unknown breed. We recorded three‐dimensional coordinate data for 31 landmarks representing various gyri, sulci, and other neuroanatomical landmarks. Placing landmarks at these locations allowed us to analyze differences in shape of the endocasts. Using geometric morphometric analysis, we found that the endocast shape variance in this sample is correlated with cephalic index and as a result, it is clear that selection for facial reduction has caused a perceivable effect on canine neuroanatomy. Furthermore, we found that the majority of the shape variance in the sample was associated with olfactory anatomy. Despite this fact, when the olfactory anatomy‐associated landmarks were excluded from the sample, the rest of the brain morphology was also correlated with cephalic index. The results of this project indicate that modern breeding practices, specifically the selection for dogs with squished faces, have significantly impacted canine neuroanatomy.

The range of cranial morphology seen in domestic dogs (Canis lupus familiaris) is a direct result of thousands of years of selective breeding. This article is the first to investigate how selection for reduced faces in brachycephalic dogs impacted the neuroanatomy of the canine brain through the analysis of endocasts. Previous research has demonstrated global effects on the shape of the bony cranium as the result of these breeding practices; however, these studies have largely focused on the bony structures of the skull and failed to consider the influence of facial reduction on the soft tissues of the brain. We generated endocasts from an existing set of clinically‐obtained CT scans representing a variety of dogs with various cranial morphologies. These dogs represented four breeds as well as a comparative sample of dogs of unknown breed. We recorded three‐dimensional coordinate data for 31 landmarks representing various gyri, sulci, and other neuroanatomical landmarks that allowed us to analyze differences in shape of the endocasts. Through geometric morphometric analyses, we determined that the endocast shape variance in this sample is correlated with cephalic index, and thus the selection for facial reduction has caused a perceivable effect on canine neuroanatomy. Additionally, we found the majority of the shape variance in the sample to be associated with olfactory anatomy; however, the rest of the morphology also correlates with cephalic index. The results of this article indicate that modern breeding practices and the selection for dogs with short faces have significantly influenced canine neuroanatomy.

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