To examine phylogenetic heterogeneity in turtle evolution, we collected thousands of high-confidence single-copy orthologs from 19 genome assemblies representative of extant turtle diversity and estimated a phylogeny with multispecies coalescent and concatenated partitioned methods. We also collected next-generation sequences from 26 turtle species and assembled millions of biallelic markers to reconstruct phylogenies from annotated regions (coding regions, introns, untranslated regions, intergenic, and others) of the western painted turtle (Chrysemys picta bellii) genome. We then measured gene tree-species tree discordance, as well as gene and site heterogeneity at each node in the inferred trees, and tested for incomplete lineage sorting and temporal patterns in phylogenomic heterogeneity across turtle evolution. We found 100% support for all bifurcations in the inferred turtle species phylogenies. However, a number of genes, sites, and genomic features supported alternate relationships between turtle taxa, and some nodes in the turtle phylogeny were well-explained by incomplete lineage sorting. There was no clear pattern between site concordance, node age, and DNA substitution rate across most annotated genomic regions, suggesting a relatively uniform proportion of informative sites drive phylogenetic inference across the evolution of turtles. We found more gene concordance at older nodes in the turtle phylogeny, and suggest that, in addition to incomplete lineage sorting, an overall lack of gene informativeness stemming from a slow rate of evolution can confound inferred patterns in turtle phylogenomics, particularly at more recent divergences. Our study demonstrates that heterogeneity is to be expected even in well resolved clades such as turtles, and that future phylogenomic studies should aim to sample as much of the genome as possible.