Development and evolution of the unique cetacean dentition

The evolutionary success of mammals is rooted in their high metabolic rate. A high metabolic rate is sustainable thanks to efficient food processing and that in turn is facilitated by precise occlusion of the teeth and the acquisition of rhythmic mastication. These major evolutionary innovations characterize most members of the Class Mammalia. Cetaceans are one of the few groups of mammals in which precise occlusion has been secondarily lost. Most toothed whales have an increased number of simple crowned teeth that are similar along the tooth row. Evolution toward these specializations began immediately after the time cetaceans transitioned from terrestrial-to-marine environments. The fossil record documents the critical aspects of occlusal evolution of cetaceans, and allows us to pinpoint the evolutionary timing of the macroevolutionary events leading to their unusual dental morphology among mammals. The developmental controls of tooth differentiation and tooth number have been studied in a few mammalian clades, but nothing is known about how these controls differ between cetaceans and mammals that retain functional occlusion. Here we show that pigs, a cetacean relative with regionalized tooth morphology and complex tooth crowns, retain the typical mammalian gene expression patterns that control early tooth differentiation, expressing Bmp4 in the rostral (mesial, anterior) domain of the jaw, and Fgf8 caudally (distal, posterior). By contrast, dolphins have lost these regional differences in dental morphology and the Bmp4 domain is extended into the caudal region of the developing jaw. We hypothesize that the functional constraints underlying mammalian occlusion have been released in cetaceans, facilitating changes in the genetic control of early dental development. Such major developmental changes drive morphological evolution and are correlated with major shifts in diet and food processing during cetacean evolution

Changes in paediatric hospital ENT service utilisation following the implementation of a mobile, indigenous health screening service

In 2009, we established a mobile ear-screening service for children in a remote community approximately 350 km north-west of Brisbane. We compared pre-implementation health service utilisation data (2006-2008) with data for the following three years. The study included only children in schools that had participated in screening since the start of the screening programme and for which data for the 6-year study period were available. In the baseline period there were 329 ear, nose and throat (ENT) outpatient appointments at the Royal Children's Hospital (RCH) in Brisbane for children from the selected catchment area. Of these, 166 (51%) were failure-to-attends (FTAs). In the following three years, there were 105 appointments, of which 40 (38%) were FTAs. In the baseline period, 100 children received surgical procedures at the RCH; in the following three years there were 43. In the three years following implementation, 136 children were booked to receive surgical procedures locally at the Cherbourg hospital, and 117 (86%) were completed. Since no other major health service changes occurred in the region during the study period, we conclude that the telemedicine-enabled screening service improved access to specialist care in the community and resulted in fewer outpatient and surgical appointments at the tertiary centre in Brisbane